Access-method-independent exchange 3

ABSTRACT

The present invention provides a virtual network, sitting “above” the physical connectivity and thereby providing the administrative controls necessary to link various communication devices via an Access-Method-Independent Exchange. In this sense, the Access-Method-Independent Exchange can be viewed as providing the logical connectivity required. In accordance with the present invention, connectivity is provided by a series of communication primitives designed to work with each of the specific communication devices in use. As new communication devices are developed, primitives can be added to the Access-Method-Independent Exchange to support these new devices without changing the application source code. A Thread Communication Service is provided, along with a Binding Service to link Communication Points. A Thread Directory Service is available, as well as a Broker Service and a Thread Communication Switching Service. Intraprocess, as well as Interprocess, services are available. Dynamic Configuration Management and a Configurable Application Program Service provide software which can be commoditized, as well as upgraded while in operation.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent applications Ser. No.08/353,905 filed Dec. 12, 1994 and issued Dec. 15, 1998 as U.S. Pat. No.5,850,518, the entire disclosure thereof, including the specification,drawings, and abstract, being hereby incorporated by reference.

BACKGROUND OF THE INVENTION RECEIVED

1. Field of the Invention

This invention relates to computer networks and communicationmanagement, and to the establishment of communication between varioususers and/or software applications.

2. Background Discussion

The term “The Information Superhighway” is commonly thought of as anextension of the Internet, a network linking hundreds of thousands ofcomputer systems together and communicating via a standard protocol.

A computer network is simply a collection of autonomous computersconnected together to permit sharing of hardware and software resources,and to increase overall reliability. The qualifying term “local area” isusually applied to computer networks in which the computers are locatedin a single building or in nearby buildings, such as on a college campusor at a single corporate site. When the computers are further apart theterm “wide area network” may be used.

As computer networks have developed, various approaches have been usedin the choice of communication medium, network topology, message format,protocols for channel access, and so forth. Some of these approacheshave emerged as de facto standards, but there is still no singlestandard for network communication. The Internet is a continuallyevolving collection of networks, including Arpanet, NSFnet, regionalnetworks such as NYsernet, local networks at a number of university andresearch institutions, a number of military networks, and increasing,various commercial networks. The protocols generally referred to asTCP/IP were originally developed for use through Arpanet and havesubsequently become widely used in the industry. The protocols provide aset of services that permit users to communicate with each other acrossthe entire Internet.

A model for network architectures has been proposed and widely accepted.It is known as the International Standards Organization (ISO) OpenSystems Interconnection (OSI) reference model. (See FIG. 10.) The OSIreference model is not itself a network architecture. Rather itspecifies a hierarchy of protocol layers and defines the function ofeach layer in the network. Each layer in one computer of the networkcarries on a conversation with the corresponding layer in anothercomputer with which communication is taking place, in accordance with aprotocol defining the rules of this communication. In reality,information is transferred down from layer to layer in one computer,then through the channel medium and back up the successive layers of theother computer. However, for purposes of design of the various layersand understanding their functions, it is easier to consider each of thelayers as communicating with its counterpart at the same level, in a“horizontal” direction. (See, e.g. The TCP/IP Companion, by Martin R.Arick, Boston: QED Publishing Group 1993, and U.S. Pat. No. 5,159,592.These, and all patents and publications referenced herein, are herebyincorporated by reference.)

As shown in FIG. 10, the lowest layer defined by the OSI model is calledthe “physical layer,” and is concerned with transmitting raw data bitsover the communication channel. Design of the physical layer involvesissues of electrical, mechanical or optical engineering, depending onthe medium used for the communication channel. The second layer, nextabove the physical layer, is called the “data link” layer. The main taskof the data link layer is to transform the physical layer, whichinterfaces directly with the channel medium, into a communication linkthat appears error-free to the next layer above, known as the networklayer. The data link layer performs such functions as structuring datainto packets or frames, and attaching control information to the packetsor frames, such as checksums for error detection, and packet numbers.

The Internet Protocol (IP) is implemented in the third layer of the OSIreference model, the “network layer,” and provides a basic service toTCP: delivering datagrams to their destinations. TCP simply hands IP adatagram with an intended destination; IP is unaware of any relationshipbetween successive datagrams, and merely handles routing of eachdatagram to its destination. If the destination is a station connectedto a different LAN, the IP makes use of routers to forward the message.

The basic function of the Transmission Control Protocol (TCP) is to makesure that commands and messages from an application protocol, such ascomputer mail, are sent to their desired destinations. TCP keeps trackof what is sent, and retransmits anything that does not get to itsdestination correctly. If any message is too long to be sent as one“datagram,” TCP will split it into multiple datagrams and makes surethat they all arrive correctly and are reassembled for the applicationprogram at the receiving end. Since these functions are needed for manyapplications, they are collected into a separate protocol (TCP) ratherthan being part of each application. TCP is implemented in the“transport layer,” namely the fourth layer of the OSI reference model.

Except as otherwise is evident from the context, the various functionsof the present invention reside above the transport layer of the OSImodel. The present invention may be used in conjunction with TCP/IP atthe transport and network layers, as well as with any other protocolthat may be selected.

As shown in FIG. 10, the OSI model provides for three layers above thetransport layer, namely a “session layer,” a “presentation layer,” andan “application layer,” but in the Internet these theoretical “layers”are undifferentiated and generally are all handled by applicationsoftware. The present invention provides for session control and forcommunicating with applications programs. Thus the present invention maybe described in accordance with the OSI theoretical model as operatingat the session layer and application layers.

“Connectivity” and “convergence” have been used to describe two aspectsof the communications and computing revolution taking place. In 1994,technology provides to communicate by telephone, pager, fax, email,cellular phone, and broadcast audio and video. However, to use thesecommunication services, you have to employ a telephone number, beepernumber, pager number, fax number, cellular number, and each of manyemail IDs, radio stations and television channels. The user isconfronted with an overabundance of methods providing such physicalconnectivity, one which will only grow in the future.

The types of physical connections are provided by various systemsincluding the Regional Bell Operating Companies, the Long DistanceCarriers, the Cellular Networks, and others providing signal-based orwireless communications. The Cable Television Industry providesconnectivity for video signals and increasingly other services.

SUMMARY OF THE INVENTION

The present invention provides a virtual network, sitting “above” thephysical connectivity and thereby providing the administrative controlsnecessary to link various communication devices via anAccess-Method-Independent Exchange. In this sense, theAccess-Method-Independent Exchange can be viewed as providing thelogical connectivity required. In accordance with the present invention,connectivity is provided by a series of communication primitivesdesigned to work with each of the specific communication devices in use.As new communication devices are developed, primitives can be added tothe Access-Method-Independent Exchange to support these new deviceswithout changing the application source code. When viewed in accordancewith the OSI model, the communication primitives operate at the level ofthe transport layer, and, to the extent appropriate, at the networklayer, and in some instances down to the data link layer, andoccasionally as needed, the physical layer.

Using the Access-Method-Independent Exchange of the present invention,anybody can provide a service. Similarly, anybody can be a client of aservice. A service can even be a client of another service. This isbecause every user and every service is identified by a uniquecommunication identifier. In accordance with the present invention,various communication points are connected together to form acommunication link.

The aforesaid identifiers are assigned to the user, or service provider,during their subscription process. For service providers, additionalinformation must be provided and added to the Thread Directory Service.This information includes the required physical connectivity to reachthe service.

When users want to access the Access-Method-Independent Exchange, theysimply supply Exchange with their unique identifiers. The BindingService validates each user and permits access to the Exchange. The usermay then connect to any registered service by simply calling theservice's communication identifier. Of course, if they are unfamiliarwith the service providers communication identifier, they can requestassistance through the Thread Directory Service. The Thread DirectoryService provides a listing of available services grouped byrelationship. The user can search for keywords, titles, or otherinformation such as service fees. Ultimately, the user can request togain access to the service.

The Access-Method-Independent Exchange is not limited to servicing aparticular geographic area and hence can easily work with foreigncountries. The Access-Method-Independent Exchange includes the abilityto provide voice or data message processing.

Access-Method-Independent Exchange Components: A Technical Overview TheThread Communication Service

At the core of the technology is the Thread Communication Service (TCS),a software utility used to administer the dynamic communications betweencomputer processes executing on a local computer, or, on a remotesystem. Two versions of the TCS have been implemented: one forintraprocess communications and a second for interprocesscommunications. The intraprocess version of the TCS is used for a singleapplication process with multiple threads of control. The interprocessversion of the TCS provides the administration of communications betweenprocesses executing in disjoint address spaces on a local, or remotecomputer system.

In the TCS everything is viewed as either being a communicationprimitive, or, a communication point. The communication primitives arethe low-level mechanisms used to provide the physical communicationbetween various processes. The processes participating in thecommunication are referred to as communication points. Two or morecommunication points are connected by a communication link using thecommunication primitives.

The Communication Primitives

The communication primitives are built using the underlying computeroperating system intraprocess and interprocess communication facilitiesand thus are operating-system-specific. On one operating system theremay be, for example, five communication primitives supported, whileanother operating system may support twenty. A communication primitivegenerally must provide for several operations to be applied such as:

Create: The ability to create an instance of the primitive

Destroy: The ability to destroy an instance of the primitive

Send: The ability to send data to the primitive

Receive: The ability to receive data from the primitive

Cycle: Send a default and receive default messages to/from the primitive

Connect: Primitive specific connection function

Disconnect: Primitive specific disconnection function

Suspend: Primitive specific suspension function

Resume: Primitive specific resumption function

Communication primitives are registered with the Thread CommunicationService for the specific operating system the TCS is executing on. Thename, the location, and certain characteristics describing thecommunication primitive are retained by the TCS for subsequent use. Inthis context, the communication primitives become a reusable asset,needing to be developed and tested only one time.

Each communication primitive has a shared object, referred to as thecommunication primitive object, describing the location of the variousoperations to be applied when using this primitive type. All primitiveshave the same communication primitive object structure. The TCS willload the communication primitive object at runtime only when requestedfor use by a communication point.

In a sense, the communication primitive can be thought of as analogousto the physical connection of a telephone on a phone network. A twistedpair telephone would use one primitive while a cellular telephone woulduse a different primitive.

The Communication Points

A process can register zero or more communication points with the TCS.Each point is said to describe a service. Note, however, that a servicecan be a client of a different service, or a client of itself. Theregistration process notifies the TCS as to the name and location of theservice, the default primitive to use for communicating to the service,and the default primitive to use when receiving messages from theservice.

The registration process also identifies certain characteristics of thecommunication point. These characteristics include system-dependentinformation, implementation-dependent information, and usage-dependentinformation. The characteristics include:

Scope: Determines if service executes as a sibling thread, or inseparate address space.

Stack: Required stack size

Idle: If service is to be idle on non-connects

Maxmsg: Maximum number of pending messages prior to suspension

Minmsg: Minimum number of pending messages at which service is resumed

Restart: Service is restartable

Termination: Method for terminating the service

Discarded: Method for discarding unwanted messages

The registered communication points are then retained by the TCS forsubsequent use. When a communication point has been registered, aprocess can request to be connected to the service.

Using the telephone model example, a communication point is theequivalent of a destination telephone. That is, you can call anindividual only by knowing the attributes describing that individual,such as a telephone number. The registered characteristics would besimilar to your name and address being entered into the phone book. TheTCS calls the TDS, if requested, to record the registered communicationpoint in the TDS.

Connecting Communication Points

When a process is executing, it may request the TCS to connect it to acommunication point. For the intraprocess communication version of theTCS, the service executes as a separate thread of control. In theinterprocess communication version of the TCS, the service executes as aseparate process.

There are several modifications permitted. First, when a communicationpoint is registered, the registering process can identify thecommunication point as a public point. As such, only one instance of theservice needs to be executing at any time. All processes requesting touse this point will share the same primitive. Alternatively, a servicecan be registered as a private service, in which case each processrequesting communication to the service will be connected to their owninstance of the service. Finally, when a service is initiallyregistered, a maximum number of connection points can be preset. Whenthis limit is reached, then all new processes requesting access to theservice will be denied, until such time as the number of currentinstantiations of the service falls below the threshold.

A single process can be connected to multiple services simultaneously.This can be accomplished through a single connection, or, thoughmultiple connections established by the process with the variousservices. In the former case, each time the process sends data, the datais actually sent to all services using the communication link. In thelatter instance, only a single destination is connected to thecommunication link.

Again, using the telephone model as an example, this is equivalent toyour calling a business associate on your telephone system. Whileconnected, you can put the call on hold and dial another associate, oryou can conference the associate in on the same call.

Mixing the Intraprocess and Interprocess Models

On systems supporting multiple threads of control within a singleprocess address space, the TCS uses a special communication point calledthe intra.sub.-p communication point to execute commands on behalf ofthe TCS within that address space. That is to say, when the applicationprocess makes its initial request to the TCS, the intra.sub.-pcommunication point will bootstrap itself as a communication pointwithin the application process address space. The TCS then issuesspecific commands to the intra.sub.-p communication point who executesthese commands on behalf of the TCS. The use of the intra.sub.-pcommunication point is essential to permit intraprocess communicationpoints while supporting interprocess communication points at the sametime.

When an application makes a request to connect with a registeredcommunication point, and that point must execute as a separate thread ofcontrol within the address space of the requesting process, then the TCSmust have a method to satisfy the request. Since the TCS itself isexecuting in a different address space, it needs a worker threadexecuting within the requesting process's address space to spawn therequested communication point thread on its behalf.

The TCS also provides a method for a intraprocess communication point tobe treated as an interprocess communication point. When an applicationprocess makes a request to use an intraprocess communication point as aninterprocess communication point, the TCS will execute a generic frontend loader to initialize the address space of the new process, and theninvokes the specific thread requested in that address space.

Communicating with a Service

Once connected, a process can send messages to a service. The primitiveto send this message must accept the message, the size of the message,and the destination. Similarly, a process can request to receive amessage from a service. In receiving the message, the process mustidentify the service it is to receive the message from, the maximumlength of a message it can consume, and the actual size of the messagereturned.

Note that from the point of view of the application process, there is noneed to be aware of the underlying physical primitive in use. Instead,the application sees that a Thread Communication Link is provided andneed not deal with how it is provided.

Disconnecting from a Service

A process can request the TCS to disconnect it from a particularservice. When this happens, the service can be terminate by the TCS ifthis was the only process connected to it. Otherwise, the serviceremains executing.

Using TCS for Remote Communication

In the TCS model, a special communication point can be created tomonitor a communication device available to the computer system. Thiscommunication point acts as the conduit to send messages to, and receivemessages from the communication device. The primitive used for thiscommunication point wraps the identifier of the sending process, alongwith the identifier of the receiving process, around the message priorto sending the data out on the communication device. Similarly, whenthis communication point receives a message from the communicationdevice, it unwraps the message to determine the process that the messageis to be sent to. In this sense, the communication point is the conduitfor communications with external systems.

The Broker Service

When a communication point is registered, the communication point mayhave a specific communication primitive required to either send orreceive message. This poses a challenge for another communication pointto connect if the requesting communication point requires a differentcommunication primitive. When this happens, the TCS will search for abroker communication point which can convert the messages from the firstprimitive type to the second primitive type. The broker service, ifnecessary, will be inserted between the requesting communication pointand the requested service communication point.

The TCS Model

In the TCS model, processes are nothing more than communication points.Application programs residing on a disk are also viewed as communicationpoints (albeit the application program must be started for execution bythe TCS). This powerful model enables application software developmentwhich may effectively commoditize software.

The Thread Directory Service

The Thread Directory Service is an extension of the Thread CommunicationService offering persistence to the registered communication primitivesand registered communication points. When a communication point isregistered with the TDS, it is assigned a unique communicationidentifier. Numerous additional characteristics of the service can beregistered within the TDS such as:

1. Textual description of the type of service

2. Sending communication primitive and receiving communication primitive

3. Communication mechanism used in establishing this service

4. Location of the service

5. Input types understood by the service

6. Output types generated by the service

7. Keyword search list used to locate this service entry

8. Token describing if the execution of the service can be started

9. Token describing the data representation in communication with theservice, i.e. binary, ASCII, etc.

10. Token describing if the execution of the service must havepreviously been started

11. Token describing if Thread Communication Identifier is listed orunlisted

12. Token describing if a public connection to the service can be used

13. Token describing if a private connection to the service can be used

14. Token describing if a public connection is mandatory

15. Token describing if a private connection is mandatory

16. Token describing if the service is a component of a larger service

17. Shell actions to execute in initializing this service

18. The maximum number of concurrent communications

19. Licensing information

20. Other general user information

21. Link to additional Services required in using this service

22. Series of status information components including but not limited tosecurity privileges and owner information.

23. Series of additional information components used for futureenhancements

24. Thread Communication Identifier

25. Secondary Thread Service Directory

26. Usage Fee

27. Directory Service Fees

Of the foregoing, items 2 and 4 are essential; the others are optional,though desirable.

A process can request information from the Thread Directory Servicespecifying the desired search criteria. This is similar to dialing 411and requesting a telephone number for an individual based on their nameand street address. Each TDS has its own unique identifier. Theregistered communication points are assigned unique communicationidentifiers based on the TDS's identifier. Thus, communication pointsare fixed in the universe in this sense.

When the Thread Communication Service works in conjunction with theThread Directory Service, all communication points to be connected arelocated via their communication identifiers.

When a connection is requested to a particular communication point, therequesting process specifies the unique communication identifier of thedesired service. The TCS causes the identifier to be looked up in theTDS to determine how to connect to the service and then provides theactual connections.

The Thread Communication Switching Service

To minimize the message flow, a Thread Communication Switching Serviceis provided as a special instance of a communication point. It acceptsmultiple communication links redirecting the communications from onecommunication point to the appropriate destination communication point.As shown in FIGS. 1 to 4, a TCSS can communicate with communicationpoints, or, to another TCSS.

Dynamic Configuration Management

Dynamic Configuration Management is a rule-based system for specifyingcomponents of software to use in constructing a Dynamically ConfiguredApplication Program. The components of software are loaded according tothe specified rules and are subsequently executed.

The Application Process constructs the Dynamically ConfiguredApplication Program in the Dynamic Configuration Management (DCM) byspecifying zero or more RULES identifying the components of theDynamically Configured Application Program, the interactions betweenthese components, the policy for evaluating these components, the orderof evaluation of these components, and a method for satisfying the RULE.The Application Process can specify zero or more data files referred toas Virtual Program Rules Files containing RULES for the DynamicallyConfigured Application Program. In this sense, the Application Processprovides the blueprint for constructing the Dynamically ConfiguredApplication Program.

The specification of a RULE includes the following information, althoughadditional information may be incorporated by the implementation:

1. A unique alphanumeric name to identify the RULE

2. A DCM operator denoting the policy for evaluating the RULE

3. Zero or more Prerequisite RULES

4. Zero or more Attributes describing characteristics of the RULE

5. A method (possibly given as NULL) for satisfying the RULE

There are two classifications of RULES supported by the DCM given asReserved Rules and Universal Rules. The Reserved Rules have specialmeaning to the DCM. The Universal Rules are specified by the ApplicationProcess. In either case, however, the Rules contain the minimuminformation described above.

A series of Reserved Rules, referred to as the Flow Rules, provide theframework for executing the Dynamically Configured Application Program.Whenever a Dynamically Configured Application Program is to be executed,the DCM begins by evaluating the Flow Rules. All other actions arederived as a result thereof. The Flow RULES include:

1. DCMINIT RULE

2. APINIT RULE

3. MAIN RULE

4. APDONE RULE

5. DCMDONE RULE

Note, however, that additional Flow Rules may be incorporated by theimplementation.

A Dynamically Configured Application Program is therefore constructed byspecifying Universal Rules as Prerequisites Rules of the Flow Rules. Inevaluating a Flow Rule, the DCM will ensure that all Prerequisite Rulesof the Flow Rule are evaluated first.

In evaluating a RULE, the DCM views the RULE name as the current rule.The evaluation process is such that the DCM will first evaluate allPrerequisite Rules of the current rule. Thus, a Prerequisite Rulebecomes the current rule and the evaluation continues with itsPrerequisite Rules.

When the current rule has no Prerequisite Rules listed, and the currentrule has never been evaluated, then the DCM will execute the method forthis rule. After executing the method for the current rule, the DCMattaches a time stamp value denoting when the current rule wasevaluated.

When the current rule has one or more Prerequisite Rules, then the DCMcompares the time stamp value of the current rule with that of itsPrerequisite Rules. If the time stamp value of the current rule is olderthan the time stamp value of its Prerequisite Rules, then the currentrule's method is executed to satisfy the rule and the time stamp valueof the current rule is updated to denote when the current rule wasevaluated. Otherwise, the current rule's time stamp value remainsunchanged and the method is not executed.

After evaluating the last Flow Rule of the Dynamically ConfiguredApplication Program, the DCM considers the application as havingcompleted and returns control back to the initial Application Process.

Initially when a RULE is specified, the DCM makes no assumptions as towhat the RULE name represents. During the evaluation of the RULE, theDCM associates the RULE name with an entity understood by the DCM. Thisis called the binding process. The list of entities understood by theDCM and their corresponding interpretation by the DCM are providedduring the initialization of the DCM. In this sense, the list ofentities can be modified and updated over time based on market demandfor new entities and their interpretations.

The binding of the RULE name to an entity understood by the DCM isdetermined by the RULE's attributes. In this sense, the ApplicationProcess can specify how the RULE is to be interpreted by the DCM.

Through the use of this method, Minor Services for an ApplicationService can be designed, implemented, tested, and distributedindependently of the corresponding Application Program. The end-user cantherefore purchase and install only those Minor Services of interest.When the Application Program is to be executed, the resultingApplication Process will dynamically configure itself to provide theavailable Minor Services.

The advantage to the computer industry is that the Minor Services, forexample, can be designed after the Application Program and soldindividually to the end user. The implications are that:

1) the base Application Program need not be altered to support theseadditional Minor Services

2) since the end-user is purchasing only those Minor Services ofinterest, the end user does not have to provide additional media storagecapacity to support unwanted Minor Services

3) additional Minor Services can be designed, implemented, tested, andinstalled after the base Application Program thus providing:

a) the designer of the Application Program the ability to design,implement, and test additional Minor Services based on new marketdemands without changing the existing base Application Program

b) the ability to design, implement, and test additional Minor Servicesspecific to an individual customer without effecting other customers. Inthis sense, all customers would have the exact same base ApplicationProgram, but potentially different installed Minor Services

4) the development of additional Minor Services can be thoroughly testedas smaller units when compared to the approach used today in which anew, monolithic representation of the Application Program must betested. The advantage herein is that the computational resourcesrequired to develop the software are decreased, the cost of testing isdecreased, and the Minor Services can be delivered to the market in ashorter time interval.

The Configurable Application Program Service

The Configurable Application Program Service provides a method todynamically reconfigure an application process. Through the CAPS, acommunication point can be dynamically replaced by another communicationpoint. This is important for realtime systems in which you would notwant to terminate the application process to replace a defective module.

The Application Process uses the Configuration Administrator MinorService to administer zero or more components of software from sharedlibraries. Each component is said to offer a Minor Service. Thespecifications for the administration of the Minor Services can beprovided directly by the Application Service, or, indirectly through adata store monitored by the Configuration Administrator. Thesespecifications can instruct the Configuration Administrator MinorService to perform the desired operation immediately, at a predefinedtime (which may be an interval), or, as a result of some event which islater communicated to the Configuration Administrator Minor Service.

The Configuration Administrator Minor Service provides the followingoperations:

1. Locates specified Minor Services

2. Loads specified Minor Services

3. Executes specified Minor Services

4. Establishes communication channel with the specified Minor Service.

5. Suspends execution of specified Minor Services

6. Resumes execution of specified Minor Services

7. Replaces specified Minor Service with a new Minor Service reroutingcommunication channels as appropriate

8. Unloads specified Minor Service

9. Provides for manual state retention between replaceable MinorServices

10. Notification

Note that the Configuration Administrator Minor Service operations canbe specified to occur at set time intervals; at predefined time periods;as a result of external events; or, as a result of internal events.Events, in this context are registered with the ConfigurationAdministrator Minor Service to denote their occurrence.

The advantage is that an Application Program can be constructed andexecuted and subsequently reconfigured to take advantage of newlyinstalled minor software services while the Application Process isexecuting. The implications of such a system are that:

1. Mission-critical Application Programs which require 24 hour, 365 daysa year execution can be reconfigured without terminating execution ofthe existing Application Process.

2. An Application Process can be reconfigured without terminating thatApplication Process which would otherwise cause the Application Processto lose all data currently held in Random Access Memory

3. An Application Process which requires a significant initializationsequence does not need to be terminated to install new minor softwareservices. Instead, the Application Process can be reconfigured ondemand.

4. New software services can be designed, implemented, and tested usingan existing Application Process such that the new services can bede-installed if found in fault without disrupting the existingApplication Process.

5. Application Processes which monitor real-time events can bedynamically reconfigured to adjust to those real-time events withoutterminating the existing Application Process.

6. Diagnostic Minor Services can be configured into an existingApplication Process for administrative, diagnostic, or statisticalanalysis and subsequently removed without affecting the existingApplication Process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Diagram showing Simple Thread Communication Link between TCP-1and TCP-2.

FIG. 2. Diagram showing Two Thread Communication Links.

FIG. 3. Diagram showing Thread Communication Switch and Three ThreadCommunication Links.

FIG. 4. Diagram showing Thread Trunk Line.

FIG. 5. Diagram showing Example Dynamically Configured ApplicationProgram Rules.

FIG. 6. Diagram showing Example Application Process.

FIG. 7. Diagram showing Reconfiguring an Application Process.

FIG. 8. Diagram showing Active NEE Takes Input from NEEM, Output Read byMinor Service Reader Threads.

FIG. 9. Diagram showing Directed Communication Types betweenCommunication Points

FIG. 10. Diagram showing Theoretical Open Systems Interconnection (OSI)Model.

FIG. 11. Pseudo Procedural Code for Example of Threaded State Machine.

FIGS. 12.A and 12.B State Machine Representation of Example of ThreadedState Machine.

The following figures show exemplary source code in the C programminglanguage, as implemented for Unix 4.2 MP TLP/5:

FIG. 13. Examples of Source Code for Binding Services.

FIG. 13.A Commands Used to Compile Binder Example.

FIG. 13.B Running Binding Service Example.

FIG. 13.C Sample Output from Binding Service

FIG. 13.D Simple Services.

FIG. 13.E Registering Binding Method and Binding Arbitrary NamedRepresenatives.

FIG. 13.F Header File Declaring Binding Method.

The following figures represent examples of data:

FIG. 13.G Examples of Pattern, Transformation, Locate, Status and Queryfor a Shared Object in a Shared Library.

FIG. 13.H Example of Shared Library Binding Method.

FIG. 13.I Example of Shared Library Binding Method including Pattern,Transformation, Locate, Status & Query.

FIG. 13.J Example of Data Structures Header File.

FIG. 13.K Example of Registering a Binding Service Method to Make SuchMethod Available to Binding Services (BSV).

FIG. 14. Samples of Particular Services.

FIG. 14.A Sample Communication Points Module.

FIG. 14.B Sample Output for Broker Data.

FIG. 14.C Sample Output for Weather Data.

The following figures show exemplary source code:

FIG. 15. Examples of Communications Modules.

FIG. 15.A Communication Data Header File.

FIG. 15.B Communication Data Module.

FIG. 16. Compoints.

FIG. 16.A Compoints Header File.

FIG. 16.B Compoints Module.

FIG. 17. Communications Registration.

FIG. 17.A Communications Registration Header File.

FIG. 17.B Communications Registration Module.

FIG. 17.C Communications Point Header File.

FIG. 17.D Communications Point Module.

FIG. 18. Thread Condition Variables.

FIG. 18.A Thread Condition Variable Header File.

FIG. 18.B Thread Condition Variable Module.

FIG. 19. Generic Compoints.

FIG. 19.A Generic Compoint Header File.

FIG. 19.B Generic Compoint Module.

FIG. 20. Thread Link Lists.

FIG. 20.A Thread Link List Header File.

FIG. 20.B Thread Link List Module.

FIG. 21. Mutex Thread Log.

FIG. 21.A Mutex Thread Log Header File.

FIG. 21.B Mutex Thread Log Module.

FIG. 22. Thread Mutex.

FIG. 22.A Thread Mutex Header File.

FIG. 22.B Thread Mutex Module.

FIG. 23. Communication Primitives.

FIG. 23.A Communication Primitive Header File.

FIG. 23.B Communication Primitive Module.

FIG. 23.C Communication Primitive Data Header File.

FIG. 23.D Communication Primitive Data Module.

FIG. 24. Thread Queue Conditions

FIG. 24.A Thread Queue Condition Header File.

FIG. 24.B Thread Queue Condition Module.

FIG. 25. Registry.

FIG. 25.A Registry Header File.

FIG. 25.B Registry Module.

FIG. 26. Minor Services Communication.

FIG. 26.A Minor Services Communication Module.

FIG. 27. Thread Reader-Writer.

FIG. 27.A Thread Reader-Writer Lock Header File.

FIG. 27.B Thread Reader-Writer Lock Module.

DETAILED DESCRIPTION OF THE INVENTION

The various aspects of the present invention can be implemented on adigital computer running an operating system that supportsruntime-loadable software modules, such as Unix SVR4.2 MP TLP/5 (UnixSystem Laboratories, a subsidiary of Novell Corporation). Such acomputer may, for example, be a Gateway 2000 computer having an Intel486 microprocessor, or any other hardware compatible with that operatingsystem. Many other operating systems may alternatively be used,including SunSoft Solaris 2.X, Microsoft Windows 95, Microsoft WindowsNT, IBM's AIX, and Hewlett-Packard HP-UX, on any hardware compatibletherewith. See, e.g. Solaris 2.2, SunOS 5.2 Reference Manual, Section 3,Library Routines (A-M) and (N-Z)(SunSoft Part No. 801-3954-10, RevisionA, May 1993).

Configurable Application Program Service

The term Application Program is used to describe a software applicationresiding on a medium accessible to the computer system.

An Application Process is said to provide some well-known service, e.g.wordprocessing, spreadsheet, graphics, etc. The Application Program maybe devised to provide a series of one or more Minor Services and aPrimary Service, which collectively constitute the Application Service.

The term Application Process, as used in this document, refers to theoverall computer representation of the Application Program's execution.In this definition, the term Application Process is defined toincorporate all processes of various “weight” including, but not limitedto, heavy weight, medium weight, and light weight processes relating tothe Application Service. A heavy-weight process executes in its ownaddress space, whereas medium-weight and light-weight processes mayexecute within the same address space. The Application Process mayconstitute one or more of these processes. Each of these processes issaid to have a Thread of execution.

A Thread, in this context, represents an execution stream of theApplication Process. The notion of a Thread can be provided by theunderlying operating system, referred to as kernel-supported threads, orcan be provided at the application level, referred to as user-levelthreads, or can be a mixture of the two. For the purposes of thisdescription, these will collectively be referred to as Threads. Notethat in a distributed environment, one or more of these Threads may beexecuting on a remote computer system.

The Application Process may be confined locally to the computer systemon which the Application Process was initially started, or may have itsexecution threads distributed among various computer systems accessibleto the computer system on which the Application Process was initiallystarted.

When a user of the computer system requests to execute an ApplicationProgram, the Application Program is loaded into the computer's memoryhaving a single Thread of execution. This initial Thread may then createadditional Threads on the local computer system, or possibly on a remotecomputer system.

The creation of a new Thread requires the Application Process to specifythe starting point of the new Thread. In procedural computer languages,for example, this would require the requesting Thread to specify theaddress of the procedure to begin as a new Thread. On someimplementations, the new Thread must be identified by its ApplicationProgram name. The implication herein is that the Application Program iscreated (i.e. compiled) with this information present.

The Application Program is therefore a static representation of awell-known functionality and is not easily able to dynamically loadadditional Threads unknown at the time the Application Program wasdeveloped. There are, however, certain Applications Programs whichprovide a listing of installed computer Application Programs eitherthrough a textual display or through a graphical representation referredto as an icon. Additionally, certain Application Processes searchspecific directories for available Application Programs to execute asApplication Co-Processes, but again, the criteria for theirrepresentation is static and unalterable by the end user.

In the textual representation, the name of the Application Program isprovided with zero or more additional information components such as theowner, the size, and/or execution privileges. This listing is shown tothe user, who may then enter the name of the application to execute.

Alternatively, when using a graphical user interface with an Icon, thename of the Application Program, its specific location on the computersystem, and other information is required to execute the Thread. Afurther limitation of the Icon is that one Application Process can bestarted by selecting the Icon, but that Application Process cannotselect a new Icon to execute as an Application Co-Process. That is tosay, the Icon is a graphical representation for the end user to select.

A limitation of both the textual and graphical representation of theavailable Application Programs is that the information displayed to theuser is dependent on the underlying operating system implementation.Certain operating systems will display the name, the size in bytes, theowner, the date created, and execution mode while others will display asubset of this information and possibly other system-dependentinformation. Regardless, however, the user cannot easily associateadditional information with the installed application in a usefulmanner. Finally, many users have manually created what has become knownas README files to describe this information.

There are many instances in which an Application Process will selectdifferent Minor Services depending on installed features, additionalsoftware available to the computer system, or due to other factorsexternal to the Application Process itself. Currently, the onlyprovisions to support such run-time changes to the Application Processare to design the Application Program with the appropriate logic.

This disadvantage to this approach, however, is that it limits theability of the Application Process to dynamically configure itself basedon available Minor Services, or due to other factors external to theApplication Process itself. Additionally, the Application Process cannotappropriately handle cases in which an available Minor Service mayconflict with another Minor Service. Once the incompatibility isdetected, the Application Process will simply print an error message andterminate its processing.

Finally, an Application Process which locates available Minor Serviceshas no simple provision for executing these Minor Services,communicating with these Minor Services, nor ensuring a proper orderingof the execution of these Minor Services.

The prior art therefore does not provide the necessary mechanisms for anApplication Process to dynamically alter its execution based on MinorServices available either locally or remotely to the computer system.Additionally, the prior art does not provide the necessary mechanismsfor the same Application Program to behave differently on two separatecomputer system offering two very different sets of Minor Serviceswithout this logic being introduced into the Application Program fromthe onset.

The prior art also does not provide the mechanisms for resolving featureconflicts in which there are two or more installed Minor Servicesavailable to the Application Process, but whose use are mutuallyexclusive. The Application Program will typically be designed to executethe first feature (“Feature A”), and then the second (“Feature B”). IfFeature B conflicts with the use of Feature A, there are no simpleremedies to support a resolution. Consider, for example, that theApplication Process performs various initialization sequences requiredfor Feature A. The Application Process may then also execute variousinitialization sequences for Feature B. During the initializationsequences for Feature A, certain values may be set in the ApplicationProcess which are inappropriate in the case of Feature B being present.

Within the prior art there are various approaches for configuration ofApplication Programs. Typically referred to as Software ConstructionUtilities, these approaches provide a rule-based system describing howan Application Program should be constructed from its correspondingapplication programming language source code. Examples of SoftwareConstruction Utilities include:

1. augmented make—“Augmented Version of Make,” UNIX System V, Release2.0 Support Tools Guide, pp: 3.1-19, April 1984.

2. build—Erickson, B., Pellegron, J. F., “Build—A Software ConstructionTool,” AT&T Bell Laboratories Technical Journal, vol. 63, No. 6, Part 2,pp: 1049-1059, July 1984.

3. make—Feldman, S., “Make—A Program for Maintaining Computer Programs,”Software—Practice and Experience, vol. 9, No. 4, pp: 256-265, April1979.

4. mk—Hume, A., “Mk: A Successor To Make,” USENIX Phoenix 1987 SummerConference Proceedings, pp: 445-457, 1987.

5. nmake—Fowler, G. S., “The Fourth Generation Make,” USENIX Portland1985 Summer Conference Proceedings, pp: 159-174, 1985.

6. Microsoft NMAKE—“Microsoft C: Advances Programming Techniques,”Microsoft Corporation, pp: 103-132, 1990.

Here, the source code provides the necessary algorithm, logic, andinstructions in a human-readable form. This source code must then becompiled into an Application Program which the computer can then loadand execute. The process of determining the necessary actions to createthe Application Program are typically controlled by a softwareconstruction Application Program (a “make” utility) which readsspecifications from a data file known as a “makefile”. This process iswell known and well understood in the computer programming profession.The makefile contains specification of the form:target.sub.-name:prerequisite.sub.-list

ACTION

to denote that a target is dependent on prerequisites. If one or more ofthe prerequisites is newer than the target, then the ACTION is performedto construct the target. Each prerequisite can be listed as a target ofanother rule. As an example, consider:

rule 1 A:B C

concatenate B and C to construct A

rule 2 B:b

copy “b” to “B”

rule 3 C:c

copy “c” to “C”

In this example, the rule to construct the target “A” shows it has adependency on prerequisites “B” and “C”. Note, however, that “B” isdependent on “b” according to the second rule, and that “C” is dependenton “c” based on rule 3. If “c” has changed since the last time “C” wasconstructed, then the ACTION for rule 3 would be performed toreconstruct C. Similarly, if “b” has changed since the last time “B” wasconstructed, then the ACTION for rule 2 would be performed toreconstruct B. Note that the ACTION for rule 2 and the ACTION for rule 3could in fact occur simultaneously since there are no other dependencieson these rules. After rule 2 and rule 3 has completed, then rule 1 cancontinue. Here, if “B” or “C” has changed since the last time “A” hasbeen constructed, then the ACTION for rule 1 will be performed toreconstruct A.

The issue of software configuration has historically been addressed byone of the following mechanisms:

1. All of the Application Program's Minor Services are developed andcompiled into the Application Program which is then sold to thecustomer. I shall refer to this “Non-featuring Software.”

2. All of the Application Program's Minor Services are developed andcompiled into the Application Program which is then sold to thecustomer. Certain Minor Services, however, will be inaccessible to thecustomer unless the customer pays additional fees. At that time, a keyfile is provided to the customer with the appropriate purchased MinorServices turned on. I shall refer to this as “Run-Time Featuring.”

3. All of the Application Program's Minor Services are developed, butduring the software construction process certain features will beselected to include in the Application Program. I shall refer to this as“Compile-Time Featuring.”

4. All of the Application Program's Minor Services are developed, butsold as separate Application Programs. In this instance, all of thecomponents representing the Application are well known. During theexecution of the Application Program, the features are tested to see ifthey are present. If a feature is not present, then it is simplyignored. I shall refer to this as “Load-Time Featuring.”

Application Programs are typically designed and distributed followingthe Non-featuring Software model. Consider, for example, that whenpurchasing a Word Processing Application you receive all of the latestfeatures available. This has the disadvantage that you are paying forfeatures which you may not need.

With “Run-Time Featuring”, the Application Program consists of themonolithic representation of the application. Thus you receive apotentially large Application Program with certain portions of theApplication Program inaccessible to you. Nonetheless, you receive thelargest possible representation. The disadvantage to this approach isthat you cannot ship the product until all features have been developed.Additionally, the customer must have enough memory and storage capacityfor the entire Application Program even though only a one Minor Servicemay have been purchased.

With Compile-Time Featuring, the source code representing theapplication has numerous sections delineated with conditional inclusionsbased on specified criteria. As an example, in the C language it iscustomary to use:

#if defined(FEATURE.sub.-A)

. . .

#elif defined(FEATURE.sub.-B)

. . .

#endif

The disadvantage to Compile-Time Featuring is that it makes the sourcecode difficult to understand. Additionally, as more Minor Services areadded, the complexity of maintaining the source code increases thusintroducing the prospects for inadvertent software errors, known asbugs.

Load-Time Featuring is not very common in the industry as there islittle perceived benefit. Considering that the Application must know thefeatures to test for, there is little advantage in this approach versusthe previously mentioned approaches.

An alternative method for dynamically configuring an application processduring execution is to use a shared library >>ARNO86!>>ATT90!>>SUNS92!.

>>ARNO86! Arnold, J, “Shared Libraries On UNIX System V,” 1986 SummerUSENIX Conference Atlanta, Ga. pp: 395-404, 1986.

>>ATT90! AT&T, “UNIX System V Release 4 Programmer's Reference Manual”,1990.

>>SUNS92! Sun Microsystems, Inc., “SunOS 5.2 Linker and LibrariesManual”, pp: 19-41, 1992.

With shared libraries, an application program references servicesavailable in the library without copying all of the text portion intothe Application Program. When the Application Program is executed, theresulting Application Process opens the shared library, loads theservice from the library, and then executes the service. The service isretained until the Application Process explicitly request that theservice is to be removed from the Application Process. The advantage ofusing shared libraries is that the underlying library can be upgraded,altered, or otherwise changed independently of the Application Program.

The disadvantage in using shared libraries in this manner is that theshared library can only be altered when there are no ApplicationProcesses referencing the shared library. Another disadvantage in usingshared libraries is that Application Programs are not normally designedto explicitly search and load services from the shared libraries ondemand.

Thus the prior art provides a mechanism to administer the ApplicationProgram software construction process based on available Minor Services.It does not, however, address the needs or requirements for dynamicreconfiguration of the Application Process. The distinction here is thatthe former approach constructs a static representation of theApplication Program while the later is a dynamic representation of theApplication Process.

Thread Directory Service

The invention provides a Thread Directory Service to administer one ormore Thread Service Directories. Through the Thread Directory Service athread can:

1. register new services,

2. remove existing services, and/or

3. query the directory to search for services.

In registering a new service, a series of attributes are provided by theregistering thread describing the type of service to be provided. Theseattributes are classified as Public or Private attributes. Publicattributes are considered public information and are accessible throughthe Thread Directory Service by any thread executing locally, orremotely. Private attributes are only accessible by the Thread DirectoryService. The administrator of the Thread Directory Service has access toall attributes. A complete description of the attributes is provided inthe Embodiment section below.

In registering a new service, the Thread Directory Service assigns aunique Thread Communication Identifier to the new service and retainsthis Identifier in the Thread Service Directory.

Once registered, any thread can call the Thread Directory Service toquery for a Thread Service by providing one or more Public Attributes.The Thread Directory Service will then search the Thread ServiceDirectory reporting the Thread Communication Identifier(s) of thoseservices matching the specified attributes. In querying the ThreadService Directory, a requesting thread can specify the search criteriaattributes using Boolean expressions.

Only the Service Thread owner, or the administrator of the ThreadDirectory Service can delete entries from the Thread Service Directory.

Thread Communication Service

The Thread Communication Service (TCS) is a computer software method fordynamically administering the communications between two or more MinorServices of an Application Process.

The TCS provides the capability to:

1. register low level communication primitives for connectivity andsynchronization

2. register Minor Services as communication points

3. begin the execution of a communication point as a Minor Service ofthe Application Process

4. remove communication points

5. connect communication points using a communication link

6. disconnect communication points

7. suspend communication links

8. resume communication links

9. terminate the execution of a communication point

10. allow a communication point to broadcast to multiple communicationpoints

11. allow a communication point to receive messages from multiplecommunication points

Thread Communication Switching Services

The Thread Communication Switching Services system has several features.It routes communications between two or more threads interconnectedthrough a Thread Communication Link. It minimizes the number of ThreadCommunication Links required to be maintained by the Thread ConnectService. It also packages multiple Thread Communication Packets into asingle packet for long distance communications. It also providesredundancy of communications in the event that a Thread CommunicationPoint in the Thread Communication Link terminates unexpectedly.

Binding Service

The Binding Service is a computer software method to dynamicallyadminister the association of one or more arbitrary namedrepresentations with entities understood by the Application Process.Each arbitrary named representation is a sequence of one or more bytesapplied at the Application Process level.

Definitions

An arbitrary named representation is initially considered as Unbound.When an association between the arbitrary named representation is madewith an entity understood by the Binding Service, then the arbitrarynamed representation is considered Bound. The process of determining theassociation is called the Binding Process. The Binding Process appliesan ordered series of Binding Methods to determine if an associationbetween an arbitrary named representation and the entities understood bythe Binding Service can be made.

To determine the significance of an arbitrary named representationwithin the scope of the Application Process, the Application Process canrequest the Binding Service to apply the Binding Methods to thearbitrary named representation to determine what entity the namerepresents.

Binding Methods

The Binding Service provides a series of Default Binding Methodsincluding the ordering of Binding Methods as should be applied by theBinding Service. These Binding Methods and their ordering are specifiedin a Binding Configuration File which is read by the Binding Serviceduring its initialization. Additional Binding Methods can be added tothe Binding Configuration File by the end user. Other Binding Methodscan be registered with the Binding Service during the ApplicationProcess' run time execution. The registration of a Binding Method mustinclude the information shown in Table 1.

TABLE 1

Binding Method Registration Information.

Order of Evaluation

Location of Binding Method

Name of Binding Method

Example descriptive Binding Methods and their definitions are shown inTable 2. An Example of implementing a Shared Library Binding Method anda Shared Object Binding Method are shown in shown in FIG. 13.E throughFIG. 13.K and are compiled using the second command line of FIG. 13.A.FIG. 13.D provides a listing of a simple minor service that is compiledusing the first command line shown in FIG. 13.I. An example execution ofthe said compiled program is shown in FIG. 13.B. The sampled output fromthe execution of said compiled program is shown in FIG. 13.C.

TABLE 2

Default Binding Methods.

File Binding Method

a method to bind the arbitrary named representation to a file accessibleby the computer system

Shell Binding Method

a method to bind the arbitrary named representation to a user levelshell

Data Binding Method

a method to bind the arbitrary named representation to a datum availableto the Application Process

Function Binding Method

a method to bind the arbitrary named representation to a function(procedure) accessible to the Application Process

Thread Binding Method

a method to bind the arbitrary named representation to a thread of theApplication Process

Process Binding Method

a method to bind the arbitrary named representation to an existingApplication Process

Each Binding Method must have associated with it the operations shown inTable 3.

TABLE 3

Binding Method Operations

Pattern Matching Method

Name Transformation Method

Locate Method

Status Method

Query Method

The Binding Method Operations

Pattern Matching: if the arbitrary named representation matches thespecified regular expression pattern, then apply the Locate Operation todetermine if the named representation can be found. If the PatternMatching Method is specified as NULL, then proceed as if the name wasmatched. If the arbitrary named representation does not match thespecified regular expression pattern, then go to the next BindingMethod.

Transformation: if the arbitrary named representation successfullycompletes the Pattern Matching operation, then apply the Transformationoperation to the arbitrary named representation and use this transformedname for subsequent operations. If the Transformation operation is notspecified for this Binding Method, then use the specified arbitrarynamed representation for subsequent operations.

Locate Operation: use the registered Locate operation to see if thearbitrary named representation can be found. If the Locate Methodreturns success, then the arbitrary named representation is consideredBOUND using this Binding Method. If the Locate operation fails, then thearbitrary named representation remains unbound.

Status Operation: given a BOUND arbitrary named representation, use thisoperation to retrieve the status information describing this entity.This includes the following information:

arbitrary name: the specified arbitrary named representation

expanded name: the expanded description to be associated with thisarbitrary named representation

owner information: description of the owner of this bound entity

status timers: includes the creation time, the last modification time,the last access time

size: the size of the entity in bytes

value: the last recorded value associated with the entity entityspecific data: entity specific data values including the size of thisdata

Query Operation: given a BOUND arbitrary named representation, reportthe status information as described by in the Status Operation.

Binding Service Interface

The Binding Service itself provides the following methods for theApplication Process:

Register register a new Binding Method

Set Order set the ordering of the Binding Methods

Unregister remove a Binding Method

Bind apply the Binding Methods on a specified arbitrary namedrepresentation

Unbind unbind the arbitrary named representation

Establish request the Binding Service to read a specified BindingService Configuration File

Report report the requested information to the Application Process. Thismay include the list of Binding Methods, the order of evaluation ofBinding Methods, and/or the characteristics of the Binding Methods

Query report the requested information on the arbitrary namedrepresentation to the Application Process

Purge delete all references to arbitrary named references that arecurrently UNBOUND.

Dynamic Configuration Management

The Dynamic Configuration Management, hereinafter sometimes referred toas the DCM, provides a method for an Application Process to dynamicallyconstruct and subsequently execute a Dynamically Configured ApplicationProgram offering an Application Service with zero or more MinorServices.

The Application Process constructs a Dynamically Configured ApplicationProgram in the DCM by specifying a series of RULES identifying thecomponents of the Dynamically Configured Application Program, theinteractions between these components, the policy for evaluating thesecomponents, the order of evaluation of these components, and a methodfor satisfying the RULE. Additionally, the Application Process canspecify zero or more data files referred to as Program Rules Filescontaining RULES for the Dynamically Configured Application Program. Inthis sense, the Application Process provides the blueprint forconstructing the Dynamically Configured Application Program eitherthrough an Application Programming Interface and through zero or modeApplication Program Rules Files. Once constructed, the ApplicationProcess can then request the DCM to execute the Dynamically ConfiguredApplication Program.

The specification of a RULE includes the information shown in Table 4,although additional information may be provided by the actualimplementation:

TABLE 4

Rule Specification Components

A unique alphanumeric name to identify the RULE

A DCM operator denoting the policy for evaluating the RULE

Zero or more Prerequisite Universal RULES

Zero or more Attributes describing characteristics of the RULE

A method (possibly given as NULL) for satisfying the RULE

There are two classifications of RULES supported by the DCM given asReserved Rules and Universal Rules. The Reserved Rules have specialmeaning to the DCM and cannot be redefined. The Universal Rules arespecified by the Application Process. In either case, however, the Rulescontain the minimum information described in Table 4.

A series of one or more Reserved Rules, referred to as the Flow Rules,provide the framework for executing the Dynamically ConfiguredApplication Program. Whenever a Dynamically Configured ApplicationProgram is to be executed, the DCM begins by evaluating the Flow Rules.All other actions are derived as a result thereof. The Flow Rules areshown in Table 5.

TABLE 5

The Flow Rules.

DCMINIT RULE

APINIT RULE

MAIN RULE

DONE RULE

APDONE RULE

DCMDONE RULE

The MAIN RULE must be specified for the Dynamically ConfiguredApplication Program to execute. The other Flow Rules (DCMINIT, APINIT,DONE, APDONE, and DCMDONE are optional).

The DCM groups all Rules with the same name together as if they werespecified as a single entity. This permits, for example, the ApplicationProcess to specify potions of a Rule during initialization sequences andthe remainder of the Rule when initialization has completed.

When the Dynamically Configured Application Program is to be executed,the DCM will evaluate each of the specified Flow Rules. In evaluating aRULE, the DCM views the RULE name as the current rule. The evaluationprocess is such that the DCM will first evaluate all Prerequisite Rulesof the current rule. Thus, a Prerequisite Rule becomes the current ruleand the evaluation continues with its Prerequisite Rules. This isimplemented using well known directed graph techniques.

When the current rule has no Prerequisite Rules listed, and the DCMdetermines the current rule must be evaluated, then the DCM will executethe method for this rule. After executing the method for the currentrule, the DCM attaches a time stamp value denoting when the current rulewas evaluated.

When the current rule has one or more Prerequisite Rules, then the DCMcompares the time stamp value of the current rule with that of itsPrerequisite Rules. If the time stamp value of the current rule is olderthan the time stamp value of its Prerequisite Rules, then the currentrule's method is executed to satisfy the rule and the time stamp valueof the current rule is updated to denote when the current rule wasevaluated. Otherwise, the current rule's time stamp value remainsunchanged and the method is not executed.

After evaluating the last Flow Rule of the Dynamically ConfiguredApplication Program, the DCM considers the application as havingcompleted and returns control back to the initial Application Process.

The policy for evaluating a RULE is determined by the DCM operatorcomponent of the RULE. By default, a TIME.sub.-VALUE operator (:) willbe applied which provides the behavior as described above. AdditionalDCM operators can be derived and implemented into the DCM to describethe relationship between the RULE and its Prerequisite Rules.

Initially when a RULE is specified, the DCM makes no assumptions as towhat the RULE name represents. During the evaluation of the RULE, theDCM uses the Binding Service to associate the RULE name with an entityunderstood by the DCM. The list of entities understood by the DCM andtheir corresponding interpretation by the DCM are provided during theinitialization of the DCM. In this sense, the list of entities can bemodified and updated over time based on market demand for new entitiesand their interpretations. The DCM provides the following defaultBinding Methods:

SHARED LIBRARY BINDING METHOD: The rule represents a shared libraryavailable to the Application Process.

SHARED OBJECT BINDING METHOD: The RULE name represents a shared objectfrom a shared library. If the RULE has a prerequisite RULE BOUND to aSHARED LIBRARY, then the shared object is presumed to exist in thatlibrary. If the method for the rule is to be executed, then the DCMopens the shared library, extracts the shared object, and executes theshared object. To specify a SHARED OBJECT BINDING METHOD, the rule musthave the Reserved Rule SHARED OBJECT as a prerequisite rule.

THREAD BINDING METHOD: The RULE name represents a procedure to invoke asa separate thread of execution within the Application Process. Tospecify a THREAD BINDING METHOD, the rule must have the Reserved RuleTHREAD as a prerequisite rule.

SHELL BINDING METHOD: The RULE name does not represent a physicalentity, but rather, its method is specified as statements to be executedby the underlying SHELL provided by the operating system. To specify aSHELL BINDING METHOD, the rule must have the Reserved Rule SHELL as aprerequisite rule.

FUNCTION BINDING METHOD: The FUNCTION BINDING METHOD associates the rulename with a function (procedure) available in the application program.The DCM will search the symbol name list for the Application Process tolocate the address of the function. If the DCM must trigger the methodfor the rule, then the function is invoked.

FILE BINDING METHOD: The rule name represents the name of a fileaccessible by the computer system.

DEFAULT BINDING METHOD: If no binding method has not been specified forthe rule, then the DCM will bind the rule name using the DEFAULT BINDINGMETHOD. The DEFAULT BINDING METHOD is to associate the rule name with afunction (procedure) available in the application program. The DCM willsearch the symbol name list for the Application Process to locate theaddress of the function. If the DCM must trigger the method for therule, then the function is invoked. If the DCM cannot locate thefunction in the Application Process's symbol table, then the RULE isconsidered to have failed.

The DCM can exist as a co-process of the Application Process, or as asibling process of the

Application Process. In the former sense, the DCM can be accessed bymultiple Application Programs thus providing a sharing of information.In the later case, the DCM resides within the Application Process. Thereare no constraints inherent in the model to preclude the use of the DCMacross multiple computer systems.

Through the use of the Dynamic Configuration Management method, MinorServices for an Application Service can be designed, implemented,tested, and distributed independently of the corresponding ApplicationProgram. The end-user can therefore purchase and install only thoseMinor Services of interest. When the Application Program is to beexecuted, the resulting Application Process will dynamically configureitself to provide the available Minor Services.

The advantage to the computer industry is that the Minor Services, forexample, can be designed after the Application Program and soldindividually to the end user. The implications are that:

1) the base Application Program need not be altered to support theseadditional Minor Services;

2) since the end-user is purchasing only those Minor Services ofinterest, the end user does not have to provide additional media storagecapacity to support unwanted Minor Services;

3) additional Minor Services can be designed, implemented, tested, andinstalled after the base Application Program thus providing:

a) the designer of the Application Program the ability to design,implement, and test additional Minor Services based on new marketdemands without changing the existing base Application Program

b) the ability to design, implement, and test additional Minor Servicesspecific to an individual customer without effecting other customers. Inthis sense, all customers would have the exact same base ApplicationProgram, but potentially different installed Minor Services

4) the development of additional Minor Services can be thoroughly testedas smaller units when compared to the approach used today in which anew, monolithic representation of the Application Program must betested. The advantage herein is that the computational resourcesrequired to develop the software are decreased, the cost of testing isdecreased, and the Minor Services can be delivered to the market in ashorter time interval.

Configurable Application Program Service

The Configurable Application Process Service is a computer softwaremethod for dynamically administering the component Minor Services of anApplication Process. The Configurable Application Process Serviceconsists of a Configuration Administrator Minor Service thread using theCommunication Manager Program Service described elsewhere in this patentapplication. Various other Minor Service threads may be created by theConfiguration Administrator as described herein.

The Application Process uses the Configuration Administrator MinorService, hereinafter referred to as the CAMS, to administer zero or morecomponents of software. Each component is said to offer a well definedapplication Minor Service hereinafter singularly and collectivelyreferred to as the AMS.

The specifications for the administration of the AMS can be provideddirectly by an Application Process, or, indirectly through a data storemonitored by the CAMS. These specifications can instruct the CAMS toperform the desired operation immediately, at a predefined time (whichmay be an interval), or, as a result of some event which is latercommunicated to the CAMS.

There are fifteen general operations available through the ConfigurableApplication Process Service given as:

1. LOCATE: locate and report the location of a specified AMS

2. LOAD: configure the specified AMS into the Configurable ApplicationProgram Service

3. EXECUTE: execute the specified AMS

4. REPLACE: replace the specified AMS with a new AMS

5. UNLOAD: unload the specified AMS from main memory

6. DUMP.sub.-MAP: dump a map of the current values of a specified AMS

7. LOAD.sub.-MAP: load a map of current values for a specified AMS

8. NOTIFICATION: notify the CAMS that the specified event has occurred

9. INSERT: insert the specified AMS in between two existing AMS

10. EXTRACT: removes specified AMS previously inserted with INSERToperation

11. SUSPEND: suspend the communications to a specified AMS

12. RESUME: resume the communications to a specified AMS

13. COMPRIMS: set the default communication primitives for an AMS

14. TERMINATE: terminate the execution of the specified AMS.

15. QUERY: report useful information on the current AMS beingadministered through the configurable Application Process Service.

Other technology which may be configured with the ConfigurableApplication Program Service includes the Binding Service as described inthis application.

The advantage to the computer industry is that an Application Programcan be constructed and executed and subsequently re configured to takeadvantage of newly installed minor software services while theApplication Process is executing. The implications of such a system arethat:

1. Mission critical Application Programs which require 24 hour, 365 daysa year execution can be re configured without terminating the existingDynamically Configured Application Process's execution.

2. An Application Process can be re configured without terminating thatApplication Process which would otherwise cause the Application Processto lose all data currently held in Random Access Memory.

3. An Application Process which requires a significant initializationsequence does not need to be terminated to install new minor softwareservices. Instead, the Application Process can be re configured ondemand.

4. New software services can be designed, implemented, and tested usingan existing Application Process such that the new services can bedeinstalled if found in fault without disrupting the existingApplication Process.

5. Application Processes which monitor real time events can bedynamically reconfigured to adjust to those real time events withoutterminating the existing Application Process.

6. Diagnostic Minor Services can be configured into an existingApplication Process for administrative, diagnostic, or statisticalanalysis and subsequently removed without affecting the existingApplication Process.

Named Execution Environment

This portion of the invention is a computer application service calledthe Named Execution Environment Manager. A series of one or moremachines interconnected through some form of a networking scheme canregister one or more arbitrary attributes describing the characteristicsof the machine. These attributes are known as the Registered EnvironmentAttributes within the Named Execution Environment. This registrationprocess can be completed by the system administrator (the owner of themachine), or can be completed by an automated Application Process whichprobes the machine to determine the default attributes of the machine.

When an Application Process requires the use of an executionenvironment, the Application Process calls the Named ExecutionEnvironment Manager and specifies one or more attributes describing therequirements of the desired execution environment. These attributes arereferred to as the Required Environment Attributes. Further, theApplication Process provides the Named Execution Environment Managerspecific information to be associated with the new environment if it canbe created. This information is called the Named Execution EnvironmentAttributes.

The Named Execution Environment Manager then selects an appropriatemachine based on a boolean evaluation of the Required EnvironmentAttributes provided by the Application Process, and the RegisteredEnvironment Attributes describing the physical machines.

When the Named Execution Environment Manager finds a machine whoseRegistered Environment Attributes satisfy the specified RequiredEnvironment Attributes, the Named Execution Environment Manager thenestablishes an execution environment on the associated physical machinefor use by the Application Process. The Named Execution EnvironmentManager then applies the various Named Execution Environment Attributesto this newly created execution environment, and retains thisinformation either in memory, or on a storage device accessible to theNamed Execution Environment Manager.

One of the Named Execution Environment Attributes specified by theApplication Process is a logical name to be associated with theexecution environment. The Application Process then provides the NamedExecution Environment Manager the logical name of an environment and arequest to execute in that environment. The Named Execution EnvironmentManager locates the associated environment and sends the ApplicationProcess's request to that environment. The request can be any commandunderstood by the environment.

The returned values from executing the Application Process's request inthe named environment is then sent to the Application Process. This isaccomplished using the Thread Communication Service as described in thispatent application.

Threaded State Machine

This part of the invention is a state machine manager thread providingthe administration of a state machine, and the administration andexecution of various components of a state machine.

EXEMPLARY EMBODIMENTS OF THE INVENTION

Without limiting the generality of the invention as summarized above,the following descriptions, taken with the accompanying Figures, furtherprovide specific examples of how the various aspects of the inventionmay be embodied in particular software. Those skilled in the art willrecognize that changes in form and details may be made therein withoutdeparting from the scope and spirit of the invention.

Thread Directory Service

A Thread Service Directory contains zero or more entries describingService Threads. A Service Thread is defined as an entity providing someform of a service which may or may not require direct interaction withan application program. Each Thread Service Directory entry containsitems 2 and 4 below, and desirably one or more of the other entriesdescribed below:

1. textual description of the type of service;

2. sending communication primitive and receiving communicationprimitive;

3. communication mechanism used in establishing this service;

4. Location of the service;

5. input types understood by the service;

6. output types generated by the service;

7. keyword search list used to locate this service entry;

8. token describing if the execution of the service can be started;

9. token describing the data representation in communication with theservice, i.e., binary, ASCII, etc.;

10. token describing if the execution of the service must havepreviously been started;

11. token describing if Thread Communication Identifier is listed or isunlisted;

12. token describing if a public connection to the service can be used;

13. token describing if a private connection to the service can be used;

14. token describing if a public connection is mandatory;

15. token describing if a private connection is mandatory;

16. token describing if the service is a component of a larger service;

17. shell actions to execute in initializing this service;

18. the maximum number of concurrent communications;

19. licensing information;

20. other general user information;

21. link to additional Services required in using this service;

22. series of status information components including but not limited tosecurity privileges and owner information;

23. series of additional information components used for futureenhancements;

24. Thread Communication Identifier;

25. Secondary Thread Service Directory;

26. Usage Fee;

27. Directory Service Fees.

Access to the Thread Service Directory is provided by the ThreadDirectory Service which executes as a separate thread but which may becalled from an application program. The Thread Directory Service offersa series of operations such as REGISTER, DELETE, QUERY, and others.

When a new Service Thread is made available to the computer system, itcan register its service by calling the Thread Directory Servicespecifying a REGISTER operation and providing the required informationalong with any optional information or attributes. Alternatively, aseparate application can register other Service Threads available to thecomputer system by calling the Thread Directory Service and specifying aREGISTER operation along with the appropriate information. This permitsa separate application program to provide this information withoutrequiring the Service Thread to register itself. Duplicate entries in agiven Thread Service Directory are not permitted. In this instance, theThread Directory Service will return an error indication to theregistering thread. In registering the Service Thread, the ThreadDirectory Service will assign a unique Thread Communication Identifierto be associated with the Service Thread. The Thread Directory Servicewill then return this identifier to the thread registering the service.

A Service Thread can subsequently request that its entry is to bedeleted from the Thread Service Directory by calling the ThreadDirectory Service and requesting a DELETE operation. Alternatively, aseparate application thread, with appropriate permissions can performthe same operation.

A thread can query the information in the Thread Service Directory bycalling the Thread Directory Service specifying a QUERY operation andproviding zero or more components of an entry on which the ThreadService Directory is to search for. This information is then madeavailable to the requesting thread.

A special Thread Directory Administrator Service is also provided to theowner of the Thread Directory Service to perform various administrativefunctions such as report generation, directory reordering, billing, andtrouble reporting. The Thread Directory Service and its componentsprovides for software what the telephone companies provide for their endusers. The entire Thread Directory Service and its components areimplemented through software and require no physical wire connection asdoes the telephone to use its service with the exception of any internalcomputer hardware.

Note that the Thread Directory Service and its representation of theThread Service Directory can be maintained on separate computerfacilities connected through some form of a communication channel suchas, but not limited to, a network, a telephone modem, a direct link,fiber connection, or wireless connection. The only caveat is that theremust be some form of communication available between these computersystems. Additionally, it is possible for the Thread Directory Serviceto establish communications through several computer systems toultimately reach one or more additional Thread Service Directories.

Thread Communication Service

The Architecture

The Thread Communication Service (TCS) is a computer software method todynamically administer the communications of two or more Minor Servicesof an Application Process. In this context, the Minor Services arereferred to as communication points.

A communication point can request the TCS to connect it to anothercommunication point and in doing so, the TCS is said to have establisheda Thread Communication Link (TCL) between the communication points.Through the TCL, a communication point can send data to the connectedcommunication point, and, can receive data from the connectedcommunication point. When a communication point no longer needs the TCL,it notifies the TCS to disconnect the TCL.

Communication Primitives

Communication primitives are the low level mechanism used to transmitand receive data between two or more communication points. Thecommunication primitives are constructed using low level operatingsystem interfaces which provide the underlying connectivity andsynchronization requirements. To use a communication primitive with theCommunication Manager, the communication primitive must provide thefollowing operations:

CREATE: allocates and initializes a new copy of the communicationprimitive

DESTROY: de-allocates a copy of the communication primitive

SEND: sends data out to the communication primitive and notifiesreceiver of pending message

RECEIVE: receives data from the communication primitive

RECONNECT: provides a method to cycle a communication primitive with aNULL message

CONNECT: a special method for perform a connection

DISCONNECT: a special method to perform a disconnect

SUSPEND: a special method to suspend the execution of this type ofcommunication primitive

RESUME: a special method to resume the execution of this communicationprimitive

Two examples of communication primitives are the: queueConditionThreadand queueConditionProcess. The queueConditionThread provides acommunication primitive between Application Services executing in thesame address space, whereas a queueConditionProcess provides acommunication primitive for use between Application Processes executingin disjoint address spaces.

queuecondition Thread Operations

The following are queueConditionThread operations:

CREATE: allocate the storage space for a QueueCondition primitive andinitialize the message queue, the condition variable and the mutex

DESTROY: de-allocates the storage space of a queueConditionThread

SEND: locks the message queue, posts the message to the queue,broadcasts the condition of the queue has changed and unlocks the queue

RECEIVE: locks the message queue, reads the message from the queue, andunlocks the queue

RECONNECT: locks the message queue, posts a NULL message to the queue,broadcasts the condition of the queue has changed and unlocks the queue

queueConditionProcess Operations

The following are queueConditionProcess operations:

CREATE: allocates the storage space for a queueConditionProcessprimitive in a shared memory segment, or a mapped memory region andinitialize the message queue, the condition variable and the mutex

DESTROY: de-allocates the storage space of the queueConditionProcessprimitive from the shared memory segment, or the mapped memory region

SEND: locks the message queue, posts the message to the queue,broadcasts the condition of the queue has changed and unlocks the queue

RECEIVE: locks the message queue, reads the message from the queue, andunlocks the queue

RECONNECT: locks the message queue, reads a NULL message from the queue,and unlocks the queue

The TCS maintains a list of available communication primitives for useby the communication points. This list is referred to as theCommunication Primitives List. The queueConditionThread andqueueConditionProcess primitives are added to this list. Each member ofthis list is a communication primitive and contains references to theavailable operations for this primitive.

The Application Process can add a member, delete a member, or querymember information from the Communication Primitive List.

Communication Primitives can be added for all low level physicalnetworks, and for higher level OSI protocols. These include NetWare,TCP/IP, X.25 communications and the likes. The only requirement is thatthe communication primitive provide the operations described above.

The Application Process can request the TCS to REGISTER a communicationprimitive for use in subsequent communications. The communicationprimitive is identified by:

1) its address within the operating system, or

2) by its reference name supported by the underlying operating system,such as a shared object from a shared library, or,

3) the Application Process can request the communication primitive to beregistered in the Thread Directory Service (see the description of TDS),or

4) the Application Process can request the BINDER SERVICE to bind theidentifiable name to an entity understood by the BINDER SERVICE.

The Communication Primitive should, however, be a loadable module thatthe underlying operating system can load as part of the ApplicationProcess requesting a connection to a communication point, as describedbelow.

The list of Communication Primitives available to the ApplicationProcess can be retained in memory, or, retained in a file on a storagemedium (disk), or, retained in the TDS, or, retained in an ApplicationProcess accessible to the requesting Application Process.

Registering Communication Points

The Application Process can requests the TCS to REGISTER a Minor Serviceas a communication point. The Minor Service is identified by:

1) its address within the operating system, or,

2) by its reference name supported by the underlying operating system,such as a shared object from a shared library, or,

3) the Application Process can request a Minor Service to be registeredin the Thread Directory Service (see the description of TDS), or

4) the Application Process can request the BINDER SERVICE to bind theidentifiable name of the service to an entity understood by the BINDERSERVICE, or,

5) by other means supported by the underlying operating system to ensurethat the operating system can resolve the reference (i.e., the bindingof the name is done by the operating system when the name is referencedin a connection).

In the registration process, the communication point can be identifiedas either a Sender communication point, a Receiver communication point,or as both a Sender and a Receiver communication point. The registrationprocess can also permit the Application Process to specify the desiredlow level communication primitive to use when the communication pointsis to Receive communications, and the communication primitive to usewhen the communication point is to Send communications. Thespecifications for the low level communication primitive can include:

1) its address within the operating system, or,

2) by its reference name supported by the underlying operating system,such as a shared object from a shared library, or,

3) the Application Process can query the list of available communicationprimitives from the TDS, or from the Application Process itself, or,

4) the Application Process can request the BINDER SERVICE to bind theidentifiable name of the communication primitive to an entity understoodby the TCS, or,

5) by other means supported by the underlying operating system to ensurethat the operating system can resolve the reference (i.e., the bindingof the name is done by the operating system when the name isreferenced).

The list of registered communication points can be retained in memory,or, retained in a file on a storage medium accessible to the computersystem, or, retained in the TDS, or, retained in an Application Processaccessible to the requesting Application Process.

Connecting Communication Points

The Application Process can request the TCS to CONNECT two communicationpoints with a TCL. In specifying the communication points, the TCSensures that one communication point is a Sender communication point andthe other communication point is a Receiver communication point.Further, the Communication Manager ensures that the Sender communicationpoint and the Receiver communication point both use the same underlyingsynchronization primitive for connectivity and synchronization. Ifeither condition is not satisfied, the Communication Manager will abortthe request and notifies the Application Process of the error condition.

Communication Point Selection

The selection of the communication points is determined by theimplementation which could include:

1) the Application Process provides the name (and possibly the location)of the Minor Service, or,

2) the Application Process calls the TDS to search for a communicationpoint based on specific criteria, or,

3) the Application Process uses the BINDER SERVICE to bind an arbitrarynamed representation to an entity understood by the TCS, or,

4) the Application Process uses the underlying operating systemimplementation to resolve the name of the entity.

Regardless of the method used, the TCS must be able to resolve the nameand location of the communication point. If the TCS cannot determine thename and location of the first communication point, it will call the TDSto determine if the name represents a Thread Communication Identifier asdescribed in the Thread Directory Service (TDS) section of thisapplication.

Creating Communication Points

If necessary (based on registration data; see the section on TDS), theTCS will start an invocation of a communication point as a separatethread of control. The invocation of a communication point can be as aseparate process, or, as a separate thread. In either case, the TCS willbegin the invocation of the Minor Service if the Minor Service must beexecuted, and if there are no administrative constraints, such as thenumber of instances of runnable Minor Services of the specified type hasbeen exhausted (See the section on TDS).

Alternatively, the Application Process can request that the TCS CREATEan instance of a particular Minor Service without specifying acommunication point that should be attached to it. This permits the TCSto begin the execution of the communication point, subject to theconstraints in the preceding paragraph), and permit the communicationpoint to perform some processing prior to having a connectedcommunication point. This is particularly useful for daemon MinorServices performing housekeeping (memory management, etc). At a latertime, the Application Process can request the TCS to connect acommunication point to this CREATED communication point.

In creating the Minor Service, the requesting Application Process canspecify if the Minor Service is to be executed as a Sender, Receiver, orboth. This information can be compared against the registeredinformation to ensure the Minor Service has desired communicationcapability. The TCS performs the following actions:

1) locate the requested service and complain if it cannot be found;otherwise establish a thread communication link for this communicationpoint (allocates memory and initializes) and record the location of theMinor Service communication point.

2) if the Minor Service communication point has the capability to send:

a) locate the communication primitive used by the Minor Service to send.

b) create an instance of the communication primitive (allocate memoryand initialize). This is accomplished by executing the communicationprimitive's CREATE operation.

c) set the minimum threshold value (when there are this many messageswaiting to be retrieved from the connected communication point, thenresume the execution of this communication point). Note that a defaultvalue of zero discontinues this feature.

d) set the maximum threshold value (when there are this many messageshaving been sent, but still not received by the connected communicationpoint, then suspend the execution of this communication point). Notethat a default value of zero discontinues this feature.

e) load the communication primitive into memory if not alreadyavailable.

f) this information (related to step 2) is stored in the Minor Servicecommunication point's thread communication link area for the sender.

3) if the Minor Service communication point has the capability toreceive:

a) locate the communication primitive used by the Minor Service toreceive.

b) create an instance of the communication primitive (allocate memoryand initialize). This is accomplished by executing the communicationprimitive's CREATE operation.

c) set the minimum threshold value (when there are this many messagewaiting to be received, then resume the execution of the sender). Notethat a default value of zero discontinues this feature.

d) set the maximum threshold value (when there are this many messageswaiting to be received, then suspend the sender). Note that a defaultvalue of zero discontinues this feature.

e) load the communication primitive into memory if not alreadyavailable.

f) this information (related to step 3) is stored in the Minor Servicecommunication point's thread communication link area for the receiver.

4) using the located communication point information, start an instanceof the communication point and notify it of the communication controlstructure as defined above.

Connecting Communication Points

The Application Process can request the TCS to connect two communicationpoints such that the communication points can communicate with eachother. If either communication point is not currently active, the TCSwill CREATE the missing communication point (see Creating CommunicationPoints).

When both communication points are created, the TCS will link the twocommunication points based on the specified communication directionwhich is given as one of:

Direction 1) the request is to connect two communication points witheach communication point being able to send and receive, or

Direction 2) the request is to connect one communication point to sendand the other communication point to receive, or

Direction 3) the request is to connect one communication point toreceive and the other communication point to send, or

Direction 4) the request is to connect one communication point toneither receive nor send, and the other communication point to neitherreceive nor send; thus ensuring the specified communication points aresimply CREATED.

For the purposes of describing the connection process, with referencefor example to FIG. 9, we describe the case of CP-A being connected toCP-B using communication direction 1 as described above:

step 1) add CP-B's receiver to CP-A's senderList.

step 2) add CP-A's sender to CP-B's receiverList.

step 3) add CP-A's receiver to CP-B's senderList.

step 4) add CP-B's sender to CP-A's receiverList.

step 5) if the CP-A service is idle, then reactivate it.

step 6) if the CP-B service is idle, then reactivate it.

For the case of CP-C being connected to CP-D using communicationdirection 2, as described above, then step 1) and step 2) are notcompleted. For the case of CP-E being connected to CP-F usingcommunication direction 3, as described above, then step 3 and step 4are not completed. For the case of CP-G being connected to CP-H usingcommunication direction 4, as described above, then step 1), step 2),step 3) and step 4) are not completed.

In this manner, the TCS establishes a communication link between the twocommunication points. In specifying a CONNECT request, the ApplicationProcess may specify only one of the two communication points.

If a Sender communication point is not specified, then the requestingApplication is Process is assumed to be the Sender communication point.If the specified Receiver communication point is not currentlyexecuting, then the TCS will issue a CREATE operation for the Receivercommunication point.

Alternatively, if the Application Process does not specify a Receivercommunication point, then the Application Process is assumed to be theReceiver communication point. If the specified Sender communicationpoint is not currently executing, then the TCS will issue a CREATEoperation for the Sender communication point.

Once connected, the Receiver communication point uses the RECEIVEoperation of its Receiver to Receive message. The Sender communicationpoint uses the SEND operation of its Sender to send message.

Note that certain communication primitives require specializedinitializations for establishing connections and hence, if thecommunication primitive contains a CONNECT function pointer, then thecommunication primitive's CONNECT function will be executed before anyother steps in this section.

Suspending Communication Points

The Application Process can request the TCS to SUSPEND a TCL currentlyin use by two communication points. In suspending the TCL, the TCS willtemporarily suspend the execution of the Sender communication points.Alternatively, if the Sender communication primitive has a specialSUSPEND operation defined, then the TCS will invoke that SUSPENDoperation.

Resuming Communication Points

The Application Process can request the TCS to RESUME a TCL currently inthe suspended state. In resuming the TCL, the TCS will resume theexecution of the Sender communication points. Alternatively, if thecommunication primitive of the SENDER has a special RESUME operationdefined, then the TCS will invoke that RESUME operation.

Disconnecting Communication Points

The Application Process can request the TCL to DISCONNECT one or morecommunication points using a TCL. In performing the disconnect, the TCStemporarily suspends the communication points, removes the current TCL,and restores the prior TCL associated with the communication points. Theexecution of the communication points are then resumed. The requestingApplication Process can specify if the TCS is to terminate either orboth of the communication points participating in the threadcommunication link being disconnected.

For each point being disconnected, the TCS will perform the followingactions:

1) if the receiver component of the communication point is defined andthe receiver communication primitive has a DISCONNECT operation defined,then the TCS will invoke that operation.

2) if the sender component of the communication point is defined and thesender communication primitive has a DISCONNECT operation defined, thenthe TCS will invoke that operation.

Destroying a Communication Point

The Application Process can request the TCS to DESTROY a communicationpoint. In doing so, the TCS will eliminate the registered informationregarding this communication points from its storage. If thecommunication point is currently executing, then the TCS sends a signalto the communication point to terminate. On some implementations, aspecial message may be sent by the TCS to the communication pointnotifying it that it is to terminate.

Reconnecting a Communication Point

An Application Process can request the TCS to RECONNECT a specifiedcommunication point. In doing so, the TCS will send a NULL message tothe communication point. This is useful to determine the state of thecommunication point and to cycle the communication primitive.

Executing a Communication Point

The Application Process can request the TCS to EXECUTE a specifiedcommunication point. In doing so, the TCS will examine its TCL for acommunication point having the specified name. If the communicationpoint is not currently executing, then TCL will issue a CREATE requestfor the specified communication point. The communication point's threadis then specified to resume execution. In this manner, a daemon MinorService can be created.

Note that if the communication point is a Receiver communication point,then the communication point will presumably block on its first call toits communication primitive's RECEIVE operation. Alternatively, if thecommunication point is a Sender Minor Service, then the communicationpoint will presumably continue to send messages using its communicationprimitive's SEND operation, and these message will remain until aReceiver communication point is connected.

EXAMPLE TCS Application Program

FIG. 14.A provides an example of registering communication points (MinorServices) and connecting the Application Process to these communicationpoints to take advantage of the Minor Service.

FIG. 14.B contains sample input for a Minor Service called the brokerservice.

FIG. 15.A contains the communication data header file used by thecommunication data module with the example TCS Application Program.

FIG. 15.B contains an example communication data module to be used withthe example TCS Application Program.

FIG. 16.A contains the communication point header file used by thecommunication point module with the example TCS Application Progra,

FIG. 16.B contains the communication point module providing the abilityto create a communication point in the example TCS Application Program.A communication point can also be destroyed using the Destroy functionof this module.

FIG. 17.A contains an example communication registration header fileused by the communication registration module with the example TCSApplication Program.

FIG. 17.B contains an example communication registration module toregister a Minor Service available to the example Application Process.

FIG. 17.C contains the example compoint header file used by the examplecompoint module with the example TCS Application Program.

FIG. 17.D contains the example compoint module describing memorymanagement functions representing the communication point with theexample TCS Application Example.

FIG. 18.A contains an example thread condition variable header file usedby the example thread condition variable module with the example TCSApplication Program.

FIG. 18.B contains an example thread condition variable module for usewith the example TCS Application Program.

FIG. 19.A contains an example generic communication point header filefor use with the example TCS Application Program.

FIG. 19.B contains an example generic communication module for use withthe example TCS Application Program.

FIG. 20.A contains an example thread link list header file for use withthe example TCS Application Program.

FIG. 20.B contains an example thread link list module for use with theexample TCS Application Program.

FIG. 21.A contains an example of a mutex thread log header file for usewith the example TCS Application Program.

FIG. 21.B contains an example of a mutex module for use with the exampleTCS Application Program.

FIG. 22.A contains an example of a thread mutex module header file foruse with the thread mutex module with the example TCS ApplicationProgram.

FIG. 22.B contains an example of a thread mutex module for use with theexample TCS Application Program.

FIG. 23.A contains an example of a communication primitive header filefor use with the communication primitive module listed in FIG. 23.B.

FIG. 23.B contains an example of a communication primitive moduleproviding a Create, Destroy, Load, and Unload function for use with theexample TCS Application Program.

FIG. 23.C contains an example of a communication primitive's data headerfile for use with the communication primitive's data module described inFIG. 23.D for use with the example TCS Application Program.

FIG. 23.D contains an example of a communication primitive's data modulefor use with said example TCS Application Program.

FIG. 24.A contains an example of a thread queue condition header filefor use with the thread queue condition module described in FIG. 24.Bfor use with said example TCS Application Program.

FIG. 24.B contains an example of a thread queue condition module for usewith said example TCS Application Program.

FIG. 25.A contains an example of a registry header file for use with theregistry module described in FIG. 25.B for use with the said example TCSApplication Program.

FIG. 25.B contains an example of a registry module for use with the saidexample TCS Application Program.

FIG. 26.A provides an example of a minor service communication moduleproviding a weather service as an available Minor Service for theApplication Process to register, create, and subsequently connect to,and a broker service as an available Minor Service for the ApplicationProcess to register, create, and subsequently connect to. These are tobe used with the said example TCS Application Program.

FIG. 27.A provides an example of a thread reader-writer lock header filefor use with the thread reader-writer module described in FIG. 27.B foruse with the said example TCS Application Program.

FIG. 27.B provide an example of a thread reader-writer module for usewith the said example TCS Application Program;

Thread Communication Switching Services

The Thread Service Directory Communication Link provides the ability fora Thread Communication Link between Application Threads and ServiceThreads. A Service Thread may establish additional Thread CommunicationLinks with other Service Threads, or Application Threads. In thiscontext, each thread is said to be a Thread Communication Point (TCP).Note: As used in this section, the term TCP does NOT refer to“Transmission Control Protocol.” In its simplest example, this is shownin FIG. 1 in which the Thread Communication Point labeled TCP-1 isconnected to the Thread Communication Point labeled TCP-2 through aThread Communication Link (TCL). See FIG. 1.

With additional Thread Communication Points becoming linked throughThread Communication Links it is possible for a particular thread torequest a Thread Communication Link to another thread already linked atsome further point. As an example, consider FIG. 2 which shows a ThreadCommunication Point labeled TCP-1 connected to a Thread CommunicationPoint labeled TCP-2 through a Thread Communication Link labeled TCL-1.Additionally, TCP-2 is connected to a Thread Communication Point labeledTCP-3 through a Thread Communication Link labeled TCL-2. In thisexample, if TCP-1 requested a link to TCP-3, an additional ThreadCommunication Link must be established. (See FIG. 2.)

Through the use of this invention, it is possible to have multipleThread Communication Points sharing a Thread Communication Link byestablishing a Thread Communication Switch to route the communicationsbetween the appropriate Thread Communication Points. As an example ofusing a Thread Communication Switch, see FIG. 3, which shows threeThread Communication Points labeled TCP-1 though TCP-3 connected to aThread Communication Switch labeled TCS-1 through Thread CommunicationLinks labeled TCL-1 through TCL-3. (See FIG. 3.)

A Thread Communication Switch can be connected to a Thread Trunk Point(TTP) which provides for communications to another Thread Trunk Pointwhich may in turn have a Thread Communications Link to a ThreadCommunication Switch or to a Thread Communication Point. This provides acommunications link over longer distances than the simple point-to-pointas described in FIG. 1. As an example of using a Thread Trunk Point, seeFIG. 4 which shows four Thread Communication Points labeled TCP-1through TCP-4 connected to a Thread Communication Switch labeled TCS-1.The TCS-1 has a Thread Communication Link to the Thread Trunk Pointlabeled TTP-1. This Thread Trunk Point in turn has a Thread Trunk Linklabeled TTL-1 to a destination Thread Trunk Point labeled TTP-2. TheTTP-2 has a Thread Communication Link to a second Thread CommunicationSwitch labeled TCS-2. The TCS-2 has Thread Communication Links to ThreadCommunication Points labeled TCP-5 through TCP-7. (See FIG. 4.)

The use of the Thread Communication Points, the Thread CommunicationLink, the Thread Communication Switch, the Thread Trunk Link, and ThreadTrunk Points can span multiple computer systems interconnected throughsome form of communications such as, but not limited to a network, adirect connection, a fiber connection, a telephone modem, and a wirelessconnection.

As will be appreciated by those skilled in the art, the specificrepresentation of the Thread Communication Link is dependent on theunderlying operating system's communications capability and itssynchronization primitives.

Binding Service

1. Overview

The Binding Service is a method, implemented in computer software, todynamically administer the association of one or more arbitrary namedrepresentations with entities understood by the Application Process.Each arbitrary named representation is a sequence of one or more bytesapplied at the Application Process level.

1.1. Definitions

An arbitrary named representation is initially considered as Unbound.When an association between the arbitrary named representation is madewith an entity understood by the Binding Service, then the arbitrarynamed representation is considered Bound. The process of determining theassociation is called the Binding Process. The Binding Process appliesan ordered series of Binding Methods to determine if an associationbetween an arbitrary named representation and the entities understood bythe Binding Service can be made.

To determine the significance of an arbitrary named representationwithin the scope of the Application Process, the Application Process canrequest the Binding Service to apply the Binding Methods to thearbitrary named representation to determine what entity the namerepresents.

1.2. Binding Methods

The Binding Service provides a series of Default Binding Methodsincluding the ordering of Binding Methods as should be applied by theBinding Service. These Binding Methods and their ordering are specifiedin a Binding Configuration File which is read by the Binding Serviceduring its initialization. Additional Binding Methods can be added tothe Binding Configuration File by the end user. Other Binding Methodscan be registered with the Binding Service during the ApplicationProcess's run time execution. The registration of a Binding Method mustinclude the information shown in Table 6.

TABLE 6

Binding Method Registration information.

Order of Evaluation

Location of Binding Method

Name of Binding Method

1.3. The Default Binding Methods

The Default Binding Methods and their definitions include those shown inTable 7.

TABLE 7

Default Binding Methods.

File Binding Method

a method to bind the arbitrary named representation to a file accessibleby the computer system

Shell Binding Method

a method to bind the arbitrary named representation to a user levelshell

Data Binding Method

a method to bind the arbitrary named representation to a datum availableto the Application Process

Function Binding Method

a method to bind the arbitrary named representation to a function(procedure) accessible to the Application Process

Thread Binding Method

a method to bind the arbitrary named representation to a thread of theApplication Process

Process Binding Method

a method to bind the arbitrary named representation to an existingApplication Process

1.4. The Binding Method Operations

Each Binding Method must have associated with it the series of bindingmethod operations shown in Table 8. The Binding Method is described tothe Binding Service through five function pointers describing thelocation of each operation. The function pointers are specified in theorder shown in Table 8.

TABLE 8

Binding Method Operations.

Pattern Matching Method

Name Transformation Method

Locate Method

Status Method

Query Method

1.4.1. Description Of Binding Method Operations

Pattern Matching: if the arbitrary named representation matches thespecified regular expression pattern, then apply the Locate Operation todetermine if the named representation can be found. If the PatternMatching Method is specified as NULL, then proceed as if the name wasmatched. If the arbitrary named representation does not match thespecified regular expression pattern, then go to the next BindingMethod.

Transformation: if the arbitrary named representation successfullycompletes the Pattern Matching operation, then apply the Transformationoperation to the arbitrary named representation and use this transformedname for subsequent operations. If the Transformation operation is notspecified for this Binding Method, then use the specified arbitrarynamed representation for subsequent operations.

Locate Operation: use the registered Locate operation to see if thearbitrary named representation can be found. If the Locate Methodreturns success, then the arbitrary named representation is consideredBOUND using this Binding Method. If the Locate operation fails, then thearbitrary named representation remains unbound.

Status Operation: given a BOUND arbitrary named representation, use thisoperation to retrieve the status information describing this entity.This includes the following information:

arbitrary name: the specified arbitrary named representation

expanded name: the expanded description to be associated with thisarbitrary named representation

owner information: description of the owner of this bound entity

status timers: includes the creation time, the last modification time,the last access time

size: the size of the entity in bytes

value: the last recorded value associated with the entity

entity-specific data: entity-specific data values including the size ofthis data

Query Operation: given a BOUND arbitrary named representation, reportthe status information as described by in the Status Operation.

1.5. Binding Service Interface

The Binding Service itself provides the following interfaces for theApplication Process:

Register: register a new Binding Method

Set Order: set the ordering of the Binding Methods

Unregistered: remove a Binding Method

Bind: apply the Binding Methods on a specified arbitrary namedrepresentation

Unbind: unbind the arbitrary named representation

Establish: request the Binding Service to read a specified BindingService Configuration File

Report: report the requested information to the Application Process.This may include the list of Binding Methods, the order of evaluation ofBinding Methods, and/or the characteristics of the Binding Methods

Query: report the requested information on the arbitrary namedrepresentation to the Application Process

Purge: delete all references to arbitrary named references that arecurrently UNBOUND.

2. The Architecture

2.1. Binding Service Initialization

The Binding Service, upon initialization will read a Binding ServiceConfiguration File containing zero or more entries of the form:

1. Order of Evaluation: is a numeric value describing the order in whichthis entry should be used in binding an arbitrary named representation

2. Location of Binding Method: is the name of a dynamically loadablemodule (which could include a shared library name) containing theBinding Method

3. Name of Binding Method: is the name of a shared object within thedynamically loadable module that contains the references to theoperations provided by the binding service.

2.2. The Binding Service Interface

2.2.1. The Register Interface

The Application Process uses the Binding Service's Register interface toregister additional Binding Methods not specified in a ConfigurationFile. The specification for the new Binding Method requires the samedata as that provided through the Configuration Files. The Registerinterface provides a mechanism to specify additional Binding Methodseven after the Binding Service has started execution.

2.2.2. The Set Order Interface

The Application Process uses the Binding Service's Set Order interfaceto establish a new order of evaluation to use when applying theregistered Binding Methods to an arbitrary named representation.

2.2.3. The Unregistered Interface

The Application Process uses the Binding Service's Unregisteredinterface to remove a Binding Method from the list of available BindingMethods. The Binding Method can be removed only after all references tothe Binding Method have completed their use of the method.

2.2.4. The Bind Interface

The Application Process applies the Binding Service's Bind interface toan arbitrary named representation. The Binding Service maintains a tablein memory of the arbitrary named representations requested to be boundby the Application Process. This table contains the collection ofarbitrary named representations previously specified to the Bindinterface on behalf of the Application Process.

The first step in applying the Bind interface is to search the table tosee if the specified arbitrary named representation has already beenBOUND. If not, then the Binding Service will create a new entry in thetable for the specified arbitrary named representation. This entryincludes the arbitrary named representation and initially is marked asunbound. If the specified arbitrary named representation is alreadylisted in the table and is marked as BOUND, then the Bind interfacecompletes successfully without further action being required. If thespecified arbitrary named representation is already listed in the table,but is marked as UNBOUND, then the Bind interface continues.

The Binding Service will then apply the Binding Methods based on thespecified order of evaluation for the Binding Methods. The arbitrarynamed representation is then BOUND using the first Binding Method tocomplete successful.

In applying the Binding Methods, the Binding Service will determine ifthe Binding Method has been loaded into memory. If not, then the BindingService uses the Location Operation for the Binding Method and the Nameof Binding Method to dynamically load the Binding Method into memory.The Binding Method is then applied given the constraints mentionedabove.

During the evaluation of the Binding Methods, the Binding Service willfirst examine the Binding Method to see if it has an associated PatternMatching operation. If so, then the arbitrary named representation iscompared against the specified expression pattern using the specifiedPattern Matching operation. If the arbitrary name does not compare withthe specified regular expression pattern then the next Binding Method isapplied. If the Pattern Matching operation is specified as NULL, or ifthe expression pattern is specified as NULL, or if the arbitrary namedrepresentation compares with the specified pattern, then the arbitrarynamed representation is considered for binding to this Binding Method.

Upon successfully completing the Pattern Matching operation, the BindingService applies the Name Transformation operation, if specified for theBinding Method. The Name Transformation operation is used to generate analternative named representation which will then be used for the Locateand the Status operations described below.

When the arbitrary named representation is considered for binding to aBinding Method, then the Binding Service will invoke the BindingMethod's Locate operation to locate the entity associated with thealternative named representation, or the arbitrary named representationif the alternative is not defined. If the Locate operation fails and apattern was specified, then the arbitrary named representation isconsidered BOUND, but not found. Otherwise, the arbitrary namedrepresentation remains UNBOUND.

Finally, when the arbitrary named representation has been BOUND, and hasbeen located, then the Binding Service applies the Binding Method'sStatus Operation to ascertain the current status of the bound entity.This information is then retained in the Binding Service's table.

The Binding Service maintains the representation of the BOUND entitywithin its scope. This information is not directly available to theApplication Process. Instead, the Application Process must use theBinding Service's Query operation to access this information.

2.2.5. The Unbind Interface

The Application Process uses the Binding Service's Unbind Interface tomark a previously bound arbitrary named representation as now beingunbound.

2.2.6. The Report Interface

The Application Process uses the Binding Service's Report interface toreport useful information on the current representation of the contentsof the Binding Service's data. This includes information relating to theBinding Methods.

2.2.7. The Query Interface

The Query interface reports the information available through the Queryoperation of the Binding Method used to bind the arbitrary namedrepresentation. If the arbitrary named representation is currentlyUNBOUND, then the Query interface returns only the name of the entity.

2.2.8. The Purge Interface

When the application calls the Binding Service's Purge interface, theBinding Service deletes all arbitrary named references in its table thatare UNBOUND at the time of the call.

Dynamic Configuration Management

The Application Process constructs a Dynamically Configured ApplicationProgram in the DCM by specifying a series of RULES identifying thecomponents of the Dynamically Configured Application Program, theinteractions between these components, the policy for evaluating thesecomponents, the order of evaluation of these components, and a methodfor satisfying the RULE. Additionally, the Application Process canspecify zero or more data files referred to as Application Program RulesFiles containing RULES for the Dynamically Configured ApplicationProgram. In this sense, the Application Process provides the blueprintfor constructing the Dynamically Configured Application Program eitherthrough an Application Programming Interface and through zero or modeApplication Program Rules Files. Once constructed, the ApplicationProcess can then request the DCM to execute the Dynamically Configured

Application Program.

Rule Specifications

The specification of a RULE includes the information shown in Table 9,although additional information may be provided by the actualimplementation:

TABLE 9

Rule Specification Components.

A unique alphanumeric name to identify the RULE

A DCM operator denoting the policy for evaluating the RULE

Zero or more Prerequisite Universal RULES

Zero or more Attributes describing characteristics of the RULE

A method (possibly given as NULL) for satisfying the RULE

Rule Classifications

There are two classifications of RULES supported by the DCM given asReserved Rules and Universal Rules. The Reserved Rules have specialmeaning to the DCM and cannot be redefined. The Universal Rules arespecified by the Application Process. In either case, however, the Rulescontain the minimum information described in Table 9.

A series of one or more Reserved Rules, referred to as the Flow Rules,provide the framework for executing the Dynamically ConfiguredApplication Program. Whenever a Dynamically Configured ApplicationProgram is to be executed, the DCM begins by evaluating the Flow Rules.All other actions are derived as a result thereof. The Flow Rules areshown in Table 10.

TABLE 10

The Flow Rules.

DCMINIT RULE

APINIT RULE

MAIN RULE

DONE RULE

APDONE RULE

DCMDONE RULE

The MAIN RULE must be specified for the Dynamically ConfiguredApplication Program to execute. The other Flow Rules (DCMINIT, APINIT,DONE, APDONE, and DCMDONE are optional).

Executing The DynamicalIV Configured Application Program

The DCM groups all Rules with the same name together as if they werespecified as a single entity. This permits, for example, the ApplicationProcess to specify potions of a Rule during initialization sequences andthe remainder of the Rule when initialization has completed.

The DCM will evaluate each of the specified Flow Rules in the ordershown in Table 10. In evaluating a RULE, the DCM views the RULE name asthe current rule. The evaluation process is such that the DCM will firstevaluate all Prerequisite Rules of the current rule. Thus, aPrerequisite Rule becomes the current rule and the evaluation continueswith its Prerequisite Rules. This is implemented using well knowndirected graph techniques.

When the current rule has no Prerequisite Rules listed, and the DCMdetermines the current rule's method must be executed, then the DCM willexecute the method for this rule. After executing the method for thecurrent rule, the DCM attaches a time stamp value denoting when thecurrent rule was evaluated.

When the current rule has one or more Prerequisite Rules, then the DCMcompares the time stamp value of the current rule with that of itsPrerequisite Rules. If the time stamp value of the current rule is olderthan the time stamp value of its Prerequisite Rules, then the currentrule's method is executed to satisfy the rule and the time stamp valueof the current rule is updated to denote when the current rule's methodwas executed Otherwise, the current rule's time stamp value remainsunchanged and the method is not executed.

After evaluating the last Flow Rule of the Dynamically ConfiguredApplication Program, the DCM considers the application as havingcompleted and returns control back to the requesting ApplicationProcess.

Evaluation Policies

The policy for evaluating a RULE is determined by the DCM operatorcomponent of the RULE. By default, a TIME.sub.-VALUE operator (:) willbe applied which provides the behavior as described above. AdditionalDCM operators can be derived and implemented into the DCM to describethe relationship between the RULE and its Prerequisite Rules.

The Application Program Rules, shown in FIG. 5, provides an example of aDynamically Configured Application Program. (See FIG. 5.)

The DCMINIT and the APINIT Rules are shown without Prerequisite Rules.When the MAIN Rule is evaluated, the DCM finds that it is dependent onRule-A and thus must evaluate Rule-A. In doing so, it finds Rule-A isdependent on Rule-B and must therefore evaluate Rule-B. The evaluationof Rule-B shows that Rule-B does not have any prerequisite Rules. AfterRule-B has been evaluated, the DCM resumes the evaluation of Rule-A.Upon completion of Rule-A, the DCM resumes the evaluation of the MAINRule. When the MAIN Rule has been completed, the DCM next evaluates theDONE Rule and finds that it has Rule-C as a prerequisite rule. Ittherefore evaluates Rule-C and then continues with the DONE Rule.Finally, the APDONE and DCMDONE Rules are evaluated.

Binding Methods

Initially when a RULE is specified, the DCM makes no assumptions as towhat the RULE name represents. During the evaluation of the RULE, theDCM uses the Binding Service to associate the RULE name with an entityunderstood by the DCM. The list of entities understood by the DCM andtheir corresponding interpretation by the DCM are provided during theinitialization of the DCM. The list of entities appear in the BindingService's Configuration File. In this sense, the list of entities can bemodified and updated over time based on market demand for new entitiesand their interpretations. Initially, the DCM provides the BindingMethods for:

SHARED LIBRARY BINDING METHOD: The rule represents a shared libraryavailable to the Application Process.

SHARED OBJECT BINDING METHOD: The RULE name represents a shared objectfrom a shared library. If the RULE has a prerequisite RULE BOUND to aSHARED LIBRARY, then the shared object is presumed to exist in thatlibrary. If the method for the rule is to be executed, then the DCMopens the shared library, extracts the shared object, and executes theshared object. To specify a SHARED OBJECT BINDING METHOD, the rule musthave the Reserved Rule SHARED.OBJECT as a prerequisite rule.

THREAD BINDING METHOD: The RULE name represents a procedure to invoke asa separate thread of execution within the Application Process. Tospecify a THREAD BINDING METHOD, the rule must have the Reserved RuleTHREAD as a prerequisite rule.

SHELL BINDING METHOD: The RULE name does not represent a physicalentity, but rather, its method is specified as statements to be executedby the underlying SHELL provided by the operating system. To specify aSHELL BINDING METHOD, the rule must have the Reserved Rule SHELL as aprerequisite rule.

FUNCTION BINDING METHOD: The FUNCTION BINDING METHOD associates the rulename with a function (procedure) available in the application program.The DCM will search the symbol name list for the Application Process tolocate the address of the function. If the DCM must trigger the methodfor the rule, then the function is invoked.

FILE BINDING METHOD: The rule name represents the name of a fileaccessible by the computer system.

DEFAULT BINDING METHOD: If no binding method has not been specified forthe rule, then the DCM will bind the rule name using the DEFAULT BINDINGMETHOD. The DEFAULT BINDING METHOD is to associate the rule name with afunction (procedure) available in the application program. The DCM willsearch the symbol name list for the Application Process to locate theaddress of the function. If the DCM must trigger the method for therule, then the function is invoked. If the DCM cannot locate thefunction in the Application Process's symbol table, then the RULE isconsidered to have failed.

Example: The following RULES are registered in the DCM:

spellCheck: libspell.so SHARED.OBJECT

report: spellCheck

In executing the report rule, the DCM will first evaluate theprerequisite “spellCheck” rule. In evaluating the spellCheck rule, theDCM will first evaluate the libspell.so rule. In evaluating thelibspell.so rule, the DCM will not find any prerequisites of the ruleand will therefore attempt to bind the libspell.so rule name. Thebinding method will match using the SHARED LIBRARY BINDING METHOD andthe name libspell.so will be BOUND to a shared library. In evaluatingthe SHARED.OBJECT rule, the DCM will recognize that the spellCheck rulename is to be interpreted as a function available in the shared librarylibspell.so. If the method for the rule is to be executed, then thespellCheck shared object is extracted from the shared library and isinvoked as a function of the Dynamically Configured Application Program.

Application Process Scope

The DCM can exist as a co-process of the Application Process, or as asibling process of the Application Process. In the former sense, the DCMcan be accessed by multiple Application Programs thus providing asharing of information. In the later case, the DCM resides within theApplication Process. There are no constraints inherent in the model topreclude the use of the DCM across multiple computer systems.

Example of Use of Invention

A Word Processing Application Program is designed. Using a standardsoftware construction utility, converting the source code to theApplication Program which in turn is sold to end-users. After theinitial market acceptance of the Word Processing Application Program,additional features are developed including a Thesaurus, a SpellChecking Feature and a Grammar Checking Feature. Each of these featuresis designed, developed, implemented and sold as separate Minor Servicesfor the Word Processing Application Service.

When a user purchases the Word Processing Application Program, theinstallation process creates a Application Program Rules file for theWord Processing Application Service. The Rules file contains:

APINIT: SetEnvironment

MAIN: WordProcessor

DONE: CleanEnvironment

SetEnvironment: setEnv

setEnv: THREAD

WordProcessor: wp

wp: THREAD

CleanEnvironment: clearEnv

clearEnv: THREAD

The Application Program Rules file is then given to the DCM to establishthe rules for the Dynamically Configured Application Program. Whenexecuted, the APINIT rule is evaluated, which causes the SetEnvironmentrule to be evaluated which in turn causes the setEnv rule to beevaluated. The setEnv rule has a THREAD prerequisite causing the DCM tobegin the procedure named setEnv as a thread of execution within theApplication Process. Similarly, the wp and clearEnv rules, whenevaluated, will cause the DCM to create a thread of execution within theApplication Process for their named procedures.

The user subsequently purchases the Spell Checker feature and theThesaurus, but not the Grammar Checking Feature. The installation of theSpell Checking Feature and the Thesaurus Feature cause the ApplicationProgram Rules file for the Word Processing Application Service to bemodified as follows:

APINIT: SetEnvironment

MAIN: WordProcessor

DONE: CleanEnvironment

SetEnvironment: setEnv setSpellEnv setThesEnv

setEnv: THREAD

setSpellEnv: SHARED.OBJECT spell.so

setThesEnv: SHARED.OBJECT thes.so

WordProcessor: wp

wp: THREAD

CleanEnvironment: clearEnv

clearEnv: THREAD

When the Dynamically Configured Application Program is executed, thefollowing actions are taken by the DCM:

The APINIT rule is evaluated. In evaluating the rule, the setEnv,setSpellEnv procedure from the spell.so shared library, and thesetThesEnv procedure from the thes.so shared library will both beexecuted during the evaluation of the APINIT rule. It is presumed thatthese procedures will modify the Application Process's data structuresto identify their existence to the wp thread.

In this manner, individual components of an Application Service aredesigned, implemented, and subsequently sold as individual units to theend user.

Configurable Application Process Service

The Configurable Application Process Service is a computer softwaremethod for dynamically administering the component Minor Services of anApplication Process. The Configurable Application Process Serviceconsists of a Configuration Administrator Minor Service thread using theCommunication Manager Program Service, hereinafter referred to as theCMPS, described in this patent application. Various other Minor Servicethreads may be created by the Configuration Administrator as describedherein.

The Application Process uses the Configuration Administrator MinorService, hereinafter referred to as the CAMS, to administer zero or morecomponents of software. Each component is said to offer a well definedapplication Minor Service hereinafter singularly and collectivelyreferred to as the AMS.

The specifications for the administration of the AMS can be provideddirectly by an Application Process, or, indirectly through a data storemonitored by the CAMS. These specifications can instruct the CAMS toperform the desired operation immediately, at a predefined time (whichmay be an interval), or, as a result of some event which is latercommunicated to the CAMS.

Other technology which may be configured with the ConfigurableApplication Process Service includes the Binding Service, as describedin this patent application, hereinafter referred to as the BSV.

There are fifteen general operations available through the ConfigurableApplication Process Service given as:

1. LOCATE: locate and report the location of a specified AMS

2. LOAD: configure the specified AMS into the Configurable ApplicationProcess Service

3. EXECUTE: execute the specified AMS

4. REPLACE: replace the specified AMS with a new AMS

5. UNLOAD: unload the specified AMS from main memory

6. DUMP.sub.-MAP: dump a map of the current values of a specified AMS

7. LOAD.sub.-MAP: load a map of the current values for a specified AMS

8. NOTIFICATION: notify the CAMS that the specified event has occurred

9. INSERT: insert the specified AMS in between two existing AMS

10. EXTRACT: removes specified AMS previously inserted with INSERToperation

11. SUSPEND: suspend the communications to a specified AMS

12. RESUME: resume the communications to a specified AMS

13. COMPRIMS: set the default communication primitives for an AMS

14. TERMINATE: terminate the execution of the specified AMS.

15. QUERY: report useful information on the current AMS beingadministered through the configurable Application Process Service.

Each of these operations is described below.

The LOCATE Operation

The LOCATE operation instructs the Configurable Application ProcessService to locate a specified AMS. The default action performed by theCAMS is to search through the current Application Process for thespecified AMS, and if not found, to search through zero or morespecified shared libraries. Once located, the CAMS returns the locationof the specified AMS.

When used in conjunction with the CMPS, the CAMS will also attempt tolocate the specified AMS as a registered communication point.

When used in conjunction with the Binding Service, the CAMS will alsoattempt to locate the specified AMS according to the specified rules forbinding as defined in the BSV.

The LOAD Operation

The LOAD operation instructs the Configurable Application ProcessService to dynamically configure a specified AMS. The default action ofthe CAMS is to dynamically load the specified AMS if the AMS had notpreviously been loaded. Alternatively, the Application Process canrequest that the Configurable Application Process Service to force theLOAD to be completed, even if there is a previously loaded version ofthe specified AMS.

When used in conjunction with the CMPS, the CAMS will register thespecified AMS as a communication point if it has not already beenregistered. Note that when used with the CMPS, the AMS may not be loadedinto memory, but simply marked as a communication point within the CMPS.In this sense, the AMS is considered to have been configured by the LOADoperation.

Note that the LOCATE operation can be combined with the LOAD operationto provide a single operation performing the desired functionality.

Once loaded, the specified AMS is added to the LOADED AMS Listmaintained by the Configurable Application Process Service.

During the LOAD operation, the Application Process can specify certainattributes describing characteristics of the specified AMS. Theseattributes may include, but are not limited to the following:

1. Communication Manager Program Service registration process attributes

2. Attribute describing if specified AMS can be suspended throughSUSPEND operation

3. Attribute describing if specified AMS can be replaced by another AMSthrough the REPLACE operation

4. Attribute describing if Minor Service can have its current statedumped through the DUMP.sub.-MAP operation.

5. Attribute describing if Minor Service can have its current statechanged by the LOAD.sub.-MAP operation

6. Attribute describing if the Minor Service can be Terminated throughTERMINATE operation

7. Attribute describing if the Minor Service can be removed from betweentwo Minor Services through the EXTRACT operation.

8. Attributes describing the MAP AREA generated by this AMS through theDUMP.sub.-MAP operation.

9. Attributes describing a de-allocation process for communicationspending to the specified AMS at the point that the AMS is terminatedthrough a TERMINATE operation.

Note that the actions associated with the LOAD operation can be deferreduntil the receipt of a specified event by the Configurable ApplicationProcess Service. If the action is to be deferred, the request is addedto the EVENT AMS List maintained by the CAMS, and no further action istaken by this operation.

The EXECUTE Operation

The EXECUTE operation instructs the Configurable Application ProcessService to begin the execution of a specified AMS. The specified AMSmust have previously been configured with the LOAD operation.

This operation adds the specified AMS to an ACTIVE AMS List maintainedby the CAMS.

The CAMS uses the CMPS to establish the necessary connectivity to thespecified Minor Service. The communication primitives used by the CMPSare determined in part by the COMPRIMS operation described below.

Note that the actions associated with the EXECUTE operation can bedeferred until the receipt of a specified event by the ConfigurableApplication Process Service. If the action is to be deferred, therequest is added to the EVENT AMS List maintained by the CAMS, and nofurther action is taken by this operation.

Note that the Application Process can specify the desired scope of theAMS to be executed. The scope must be specified as:

PRIVATE: a private version of the AMS must be executed.

PUBLIC: establish connectivity to an existing executing AMS, or start anew version of the AMS.

In either event, the Configurable Application Process Service maintainsa reference for the number of executions of the AMS currently in use.

The REPLACE Operation

The REPLACE operation specifies that the Configurable ApplicationProcess Service is to replace a specified ACTIVE AMS with a differentspecified AMS. The existing AMS must have been started using the EXECUTEoperation (thus must appear on the ACTIVE AMS List). The REPLACEoperation searches the ACTIVE AMS List for the specified AMS to replace.If not found, then the operation is aborted. The new AMS replacing theexisting AMS must have previously been configured with the LOADoperation and must therefore appear in the LOADED AMS List.

The CAMS will replace the existing AMS with the new AMS and reroute thecommunications previously destined for the existing AMS to the new AMS.

The Application Process must specify the disposition of the existing AMSwhich describes to the Configurable Application Process Service what isto happen to the existing AMS upon replacement by the new AMS. Thedisposition can be one of:

TERMINATE: the existing AMS is to be terminated according to theTERMINATE operation described below upon successful replacement by thenew AMS.

SUSPEND: the existing AMS is to be suspended according to the SUSPENDoperation described below.

STACK: the existing AMS is to be suspended, and a link is to bemaintained from the new AMS to the existing AMS such that upontermination of the new AMS, the existing AMS will be resumed and allcommunications to be re-established.

DAEMON: the existing AMS is to be left untouched, although no newcommunications will be permitted to that AMS.

Details on the REPLACE operation are provided in the section titled“Replace Operation Detailed Architecture.”

Note that the actions associated with the REPLACE operation can bedeferred until the receipt of a specified event by the ConfigurableApplication Process Service. If the action is to be deferred, therequest is added to the EVENT AMS List maintained by the CAMS, and nofurther action is taken by this operation.

The SUSPEND Operation

The SUSPEND Operation specifies that the Configurable ApplicationProcess Service is to temporarily suspend the execution of the specifiedAMS which was previously invoked through the EXECUTE operation and canbe found on the ACTIVE AMS List. Note that the actual suspension may beimplemented differently on various computer systems depending on thelower level operating system instructions available for theimplementation. Regardless, however, the SUSPEND Operation is guaranteedto suspend the execution of the specified AMS. Once suspended thespecified AMS is moved from the ACTIVE AMS List to the SUSPENDED AMSList.

Note that the actions associated with the SUSPEND operation can bedeferred until the receipt of a specified event by the ConfigurableApplication Process Service. If the action is to be deferred, therequest is added to the EVENT AMS List maintained by the CAMS, and nofurther action is taken by this operation.

The RESUME Operation

The RESUME Operation specifies that the Configurable Application ProcessService is to resume the execution of an AMS previously suspended withthe SUSPEND operation. Once resumed, the AMS is moved from the SUSPENDEDAMS List to the ACTIVE AMS List.

Note that the actions associated with the RESUME operation can bedeferred until the receipt of a specified event by the ConfigurableApplication Process Service. If the action is to be deferred, therequest is added to the EVENT AMS List maintained by the CAMS, and nofurther action is taken by this operation.

The DUMP MAP Operation

The DUMP.sub.-MAP operation specifies that the Configurable ApplicationProcess Service is to send a DUMP.sub.-MAP request to the specified AMS.The specified AMS must currently be on the ACTIVE AMS List.

The CAMS will allocate a storage area, referred to as the MAP AREA forthe specified AMS and associate an identifier with this MAP AREA. TheCAMS will mark the MAP AREA with administrative information including,but not limited to the specific machine architecture on which thespecified AMS is currently executing, timing information, securityinformation to prevent unauthorized access to the MAP AREA, ownershipinformation indicating the specified AMS as the owner of this MAP AREAand other information.

It is expected that upon receipt of the DUMP.sub.-MAP request, the AMSwill write to the MAP AREA that information described by its MAP AREAattributes. This data is written in a machine independent format.

The Application Process can specify to the CAMS the persistence criteriafor this MAP AREA. This information is used to determine when the CAMSis de-allocate the MAP AREA. The options are to keep the MAP AREA untilthe specified AMS terminates with the TERMINATE Operation, or, to keepthe MAP AREA until a LOAD.sub.-MAP Operation specifying this MAP AREA isissued by the Application Process

The DUMP.sub.-MAP Operation, upon completion, informs the ApplicationProcess of the identifier associated with MAP AREA.

The LOAD MAP Operation

The LOAD.sub.-MAP operation specifies that the Configurable ApplicationProcess Service is to send a LOAD.sub.-MAP request to the specified AMS.The operation requires the specification of a particular MAP AREA to beloaded. The specification of the MAP AREA may be through the identifierassigned during a DUMP MAP operation, or specified values supplied bythe Application Process.

Once the LOAD.sub.-MAP operation has completed, the CAMS determines ifthe specified MAP AREA is to be de-allocated based on the persistencevalue set by the DUMP.sub.-MAP operation, and if necessary, willde-allocate this MAP AREA.

The TERMINATE Operation

The TERMINATE operation specifies to the Configurable ApplicationProcess Service that the execution of the specified AMS is to beterminated. In performing the termination, the Configurable ApplicationProcess Service will decrement the reference count associated with thatAMS. If the reference count is non-zero, then other instances of the AMSare still in use. If the AMS was executed with a PUBLIC scope and theAMS reference count is non-zero, then no additional action is requiredby the Configurable Application Process Service. Upon termination, theAMS is removed from the ACTIVE AMS List.

All pending communications to the specified AMS are de-allocatedaccording to the De-allocation Attribute specified during the LOADOperation for the specified AMS. Note that in certain cases, this mayresult in the pending communications remaining untouched, and not beingde-allocated.

When used in conjunction with the CMPS, the communications to thespecified AMS will be terminated through a disconnect operation suppliedby the CMPS.

Note that the actions associated with the TERMINATE operation can bedeferred until the receipt of a specified event by the ConfigurableApplication Process Service. If the action is to be deferred, therequest is added to the EVENT AMS List maintained by the CAMS, and nofurther action is taken by this operation.

The NOTIFICATION Operation

The NOTIFICATION operation specifies to the Configurable ApplicationProcess Service that a particular internal or external event hasoccurred. The Configurable Application Process Service searches theEVENT AMS List to determine the any actions it is to perform based onthe receipt of this event, and then performs these actions.

The INSERT Operation

The INSERT operation specifies that the Configurable Application ProcessService is to insert the specified AMS between two specified AMS'spreviously started with the EXECUTE operation. Note that the specifiedAMS being inserted must appear in the ACTIVE AMS List.

Note that the actions associated with the INSERT operation can bedeferred until the receipt of a specified event by the ConfigurableApplication Process Service. If the action is to be deferred, therequest is added to the EVENT AMS List maintained by the CAMS, and nofurther action is taken by this operation.

The EXTRACT Operation

The EXTRACT operation is the inverse of the INSERT operation. Itspecifies that the Configurable Application Process Service is toextract a specified AMS from between two other specified AMS's. Notethat the Application Process can specify the disposition of theextracted AMS which must be one of:

TERMINATE: the extracted AMS is to be terminated according to theTERMINATE operation described above.

SUSPENDED: the extracted AMS is to be suspended according to the SUSPENDoperation described above.

Note that the actions associated with the EXTRACT operation can bedeferred until the receipt of a specified event by the ConfigurableApplication Process Service. If the action is to be deferred, therequest is added to the EVENT AMS List maintained by the CAMS, and nofurther action is taken by this operation.

The COMPRIMS Operation

The COMPRIMS operation specifies the default communication primitives tobe used by the Application Process when communicating with an AMS. Notethat the Communication Manager can adjust these primitive specificationsas necessary to ensure the proper communication link between theApplication Process and the AMS. Note further that any existingcommunication links created prior to the execution of this operationremain untouched. In this manner the Application Process can reset itsdefault communication primitive as needed.

The UNLOAD Operation

The UNLOAD operation specifies that the Configurable Application ProcessService is to unload the specified Minor Service from memory. Thespecified Minor Service cannot currently be on the ACTIVE AMS List, orthe operation is aborted. The specified Minor Service is then removedfrom the LOADED AMS List.

The QUERY Operation

The QUERY operation specifies that the Configurable Application ProcessService is to report specified information based on the current liststhat it maintains. This information may include, for example, the listof all outstanding requests pending on the receipt of an event. Thisinformation is then made available to the Application Process.

The REPLACE Operation Detailed Architecture

An AMS may be executing as a separate thread of execution, eitherlocally on the same machine as the CAMS, or remotely on a machineaccessible to that machine on which the CAMS is executing. To replacethis AMS with another AMS, the default actions taken by the ConfigurableApplication Process Service is given as:

1. SUSPEND input communications to the specified AMS.

2. Permits existing AMS output to be directed towards ApplicationProcess, but monitors the output channel for special ConfigurationMessages.

3. Begins execution of new AMS potentially as a separate thread ofexecution.

4. Issues a DUMP.sub.-MAP operation for the specified existing AMS

5. Issues a LOAD.sub.-MAP operation to new AMS using the DUMP AREAcreated in 4.

6. Redirects all input destined for existing AMS to the new AMS.

7. Multiplexes output from existing AMS and new AMS to the ApplicationProcess-or-multiplexes output from existing AMS as input to the AMS.

8. Handles disposition of the existing AMS as specified by theApplication Process.

Note that Step 2 is performed using the Thread Communication SwitchingService described in this patent application.

Example Discussion

An example of an Application Process using a Primary Service and threeMinor Services is shown in FIG. 6. Here, the Primary Servicecommunicates with each of the Minor Services using a communication linkprovided by the CMPS. (See FIG. 6.)

To reconfigure the Application Program to use AMS D in place of AMS C, aREPLACE operation is applied. Upon receipt of this request, the CAMSwill temporarily suspend the input channel to AMS C (from the PrimaryService). It then loads AMS D. The input channel to AMS D is thenestablished from the Primary Service as a replacement for input channelto AMS C. The CAMS then applies the specified disposition to AMS C. (SeeFIG. 7.)

Named Execution Environment

Overview

A Named Execution Environment, hereinafter referred to as NEE, is anexecution environment created by the Named Execution Environment Manageron behalf of a requesting Application Process. The Application Processrequesting the creation of the NEE is referred to as the Owner of theNEE. The Application Process does not know, nor cares where the NEE isphysically located, only that the binding of the NEE to the physicalexecution environment by the Named Execution Environment Managersatisfies the REQUESTED ATTRIBUTE expression as specified by the Ownerof the NEE. Through the creation process, the Owner of the NEE specifiesa logical name to be associated with the NEE, and provides additionalattributes describing the usage of the NEE. All subsequent references tothe NEE by the Owner of the NEE, or by other Application Processesspecify the logical name of the NEE, the operation to be performed, andother parameters to be used. The underlying physical connectivity andphysical information passing is then handled by the Named ExecutionEnvironment Manager.

The Named Execution Environment Configuration File

A user or Application Process of a computer system registers with theNamed Execution Environment Manager, hereinafter referred to as theNEEM, a set of one or more attributes describing an environmentavailable on the computer system. These attributes, known as theREGISTERED ATTRIBUTES may include, but are not limited to those shown inTable 11.

Multiple REGISTERED ATTRIBUTES SETS can be registered for a singlecomputer system. The REGISTERED ATTRIBUTES, along with the name of thecomputer system are stored in memory, or on a storage media accessibleto the computer system on which the NEEM is executing. A permanent copyof the REGISTERED ATTRIBUTES along with their computer system name canbe stored in the Named Execution Environment Configuration File,hereinafter referred to as the NEECF. stored in memory, or on a storagemedia accessible to the computer system on which the NEEM is executing.A permanent copy of the REGISTERED ATTRIBUTES along with their computersystem name can be stored in the Named Execution EnvironmentConfiguration File, hereinafter referred to as the NEECF.

TABLE 11

The Registered Environment Attributes.

1. Attributes describing the operating system

2. Attributes describing the underlying hardware

3. Attributes describing installed software

4. Attributes describing access methods

5. Attributes describing physical execution environment

6. Attributes describing security requirements

7. Attributes describing default shell

8. Attributes with special meaning to an application process, or user

9. Attributes describing maximum number of connections to theenvironment

10. Attributes describing the environment's physical computer system

11. Attributes describing access method to physical computer system

12. Attributes describing functionality to be associated with theenvironment

13. Attributes describing the communication identifier describing thephysical machine as a communication point of the Communication ManagerService as described in this patent application.

Executing the Named Execution Environment Manager

The NEEM executes as a co-process of the Application Process. As such,the Named Execution Manager (the NEEM) is either linked with theApplication Program directly (either through static or dynamic linkage),is executed as a separate process on a computer system accessible to thecomputer system executing the Application Process, or, is invokedthrough the Dynamic Configuration Management described in this patentapplication.

In any case, when the NEEM is executed, it reads the NEECF, detailingthe REGISTERED ATTRIBUTES describing the computer system. Note thatadditional REGISTERED ATTRIBUTES can be subsequently added (registered),deleted, or otherwise modified even after the NEEM is executing.

The entries in the NEECF may include specifications identifying remotecomputer system accessible to the current computer system through someform of communications mechanism. Such an entry includes informationdetailing if the remote computer system is expected to have a NEEMexecuting on it, and/or, if there is a NEECF located on that computersystem.

The NEEM creates a Minor Service thread, known as the NEEM STATUS THREADto periodically poll the remote computer systems identified in the NEECFand performs a statistical analysis to determine their state. If aremote computer system fails, or if the communications between the localcomputer system and the remote computer system fails, then the NEEStatus Thread will mark the remote computer system as UNACCESSIBLE bythe NEEM. At such time as the NEE Status Thread can re-establish contactwith the failed remote computer system, the NEEM will mark the computersystem as ACCESSIBLE by the NEEM.

Initially, each entry of the NEECF is read by the NEEM and itscorresponding NEE is placed on an INACTIVE NEE List maintained by theNEEM. As new Named Execution Environments are created, the NEEM addsthem to the ACTIVE NEE List.

Creating A Named Execution Environment

The Application Process makes a request to create a new NEE, byspecifying, in a Boolean Expression, one or more REQUESTED ATTRIBUTES.The Application Process also specifies one or more NEE ATTRIBUTESincluding, but not limited to:

a logical name to be associated with the newly created environment.

an attribute describing if the NEE is PUBLIC or PRIVATE

an attribute describing if the NEE is to only execute foregroundcommands.

an attribute describing if the NEE is to only execute backgroundcommands.

an attribute describing if other processes can execute in theforeground.

an attribute describing if other processes can execute in the background

an attribute describing where the output is to be sent

an attribute describing CPU threshold values

an attribute describing if NEE is to be suspended when not in use

an attribute describing the shell Application Process to execute in thisNEE

an attribute describing if the NEE can be terminated by any process

an attribute describing seconds of IDLE time prior to termination of theNEE

an attribute describing if NEE is to be terminated upon the terminationof owner

The NEEM searches the REGISTERED ATTRIBUTE entries for an environmentsatisfying the REQUESTED ATTRIBUTES set forth by the ApplicationProcess. When a match has been found, then the NEEM will establish ashell on the associated computer system to execute the requests of theApplication Process. The newly created environment then becomes anACTIVE NEE, and is added to the ACTIVE NEE List maintained by the NEEM.

Note that if the REQUESTED ATTRIBUTES can be satisfied by an ACTIVE NEEwith a PUBLIC NEE ATTRIBUTE, then the NEEM will simply alias thespecified logical name with the previous specified logical name of thecurrent ACTIVE NEE satisfying the request. The reference countassociated with this ACTIVE NEE is then incremented.

Just prior to executing the shell Application Process associated with anew ACTIVE NEE, the NEEM will arrange for the standard input, thestandard output, and the standard error file descriptors to beredirected to/from the NEEM itself. In this manner, the NEEM will beable to appropriately redirect all I/O requests on this file descriptorsappropriately. The NEEM will also establish Minor Service Reader/Writerthreads to read the standard output and standard error file descriptorsand to redirect this output to the appropriate Application Processmaking a request to execute in the ACTIVE NEE. This is shown in FIG. 8.

Using a Named Execution Environment

An Application Process can request the NEEM to execute a request in aspecific NEE by specifying the logical name of the NEE. The NEEM willlook up the logical name in its ACTIVE NEE List and will send therequest to that named environment. At this point, the ApplicationProcess is considered ATTACHED to the logically named NEE and can readits standard output and its standard error through the NEEM. When theNEEM determines that the request has completed, the NEEM willautomatically DETACH the Application Process from the logically namedNEE.

Using a standard Application Programming Interface, the ApplicationProcess can read the standard output of the logically named NEE to whichit is ATTACHED. This is accomplished by the Minor Service Reader/WriterThread of the NEEM that is reading the actual standard output of theNEE. It will send the standard output to the Application Process.Likewise, the Minor Service Reader/Writer Thread of the NEEM which readsthe actual standard error will send the standard error output to theApplication Process.

There are a series of commands understood by the NEEM through which theApplication Process can control the use of a logically named NEE. Theseinclude:

1. EXECUTE: the Application Process specifies a request to be executedin a logically named NEE. The logically-named NEE must have previouslybeen created. Additional attributes can be specified to describe thecharacteristics of the execution itself. These include, but are notlimited to:

A. FOREGROUND: the request is to be executed in the foreground

B. BACKGROUND: the request is to be executed in the background

C. PERIOD: the request must complete within a specified time period

2. QUERY: the Application Process can query the NEEM for specifiedinformation related to ACTIVE, or INACTIVE logical environments.

3. REDIRECT: the Application Process owner of the logically named NEEcan request that the standard input, standard output, and/or thestandard error output be redirected from the logically named NEE toanother NEE.

4. DUPLICATE: the Application Process can request that the NEEM make aduplicate copy of a specified logically named NEE. The ApplicationProcess specifies a new logical name for the duplicate environment.

5. SUSPEND: the Application Process owner of the specified logicallynamed NEE can request the NEEM to suspend subsequent requests for thisNEE. All requests remain pending until the NEE is either RESUMED, thepending requests are CANCELED, or, the NEE is terminated.

6. RESUME: the Application Process owner of the specified logicallynamed NEE can request the NEEM to resume the previously suspended NEE.All pending requests of this NEE are then acted upon given theconstraints of the EXECUTE command as described above.

7. CANCEL: the Application Process owner of the specified logicallynamed NEE can request the NEEM to cancel all pending requests for thespecified NEE.

Terminating a Named Execution Environment

The owner of the Named Execution Environment can terminate the NamedExecution Environment by sending a TERMINATE request to the NamedExecution Environment Manager.

Threaded State Machine

The application program defines a set of states describing a statemachine with exactly one start state, and potentially many different endstates. The application then attaches a datum to the State Machine. TheState Machine Thread Manager then administers the transition of thisdatum through the state machine.

For each defined state, there is a corresponding state thread. When adatum enters a particular state, the State Machine Thread Managerinvokes the State Thread as a separate thread of execution. The exitingvalue of this State Thread is then used to determine the next transitionfrom the current state. In this manner, various datums maysimultaneously be attached to the same Multithreaded State Machine andthe State Machine Thread Manager will administer and synchronize theirtransitions simultaneously.

Finally, the State Machine Thread Manager provides a special “Error”state to which a datum will transition when the exiting value of theState Thread is undefined in the current state machine.

Example of Use of the Invention

Software construction is the process of compiling source code componentsto produce a binary representation. In this instance, a rulespecification of the form:

target.sub.-name: prerequisite.sub.-list

action is specified to show that a target is dependent on prerequisites.If one or more of the prerequisites are newer than the target, then theaction is triggered to construct the target. Each prerequisite can belisted as a target of another rule. As an example, consider:

rule 1 A: B C

concatenate B and C to construct A

rule 2 B: b

copy “b” to “B”

rule 3 C: c

copy “C” to “C”

In this example, the rule to construct the target “A” shows it has adependency on prerequisites “B” and “C”. Note, however, that “B” isdependent on “b” according to the second rule, and that “C” is dependenton “c” based on rule 3. If “c” has changed since the last time “C” wasconstructed, then the action for rule 3 would be triggered toreconstruct C. Similarly, if “b” has changed since the last time “B” wasconstructed, then the action for rule 2 would be triggered toreconstruct B. Note that the action for rule 2 and the action for rule 3could in fact occur simultaneously since there are no other dependencieson these rules. After rule 2 and rule 3 has completed, then rule 1 cancontinue. Here, if “B” or “C” has changed since the last time “A” hasbeen constructed, then the action for rule 1 will be triggered toreconstruct A.

Using a procedural language, the algorithm to provide this service canbe specified as shown in FIG. 11 Using a state machine representation,the same algorithm would be given according to FIGS. 12A and 12B.

Having thus described the invention, what it is desired to claim andthereby protect by Letters Patent is:
 1. A method to selectively use anApplication Process to both access information, and to access andinteract with Minor Services that have been referenced in therepresentation of the application program for the recorded ApplicationProcess comprising the steps: a) selecting registered Minor Services andregistered communication primitives by chosen criteria; b) determiningwhich selected Minor Services and communication primitives are presentlyloaded; c) loading said selected Minor Services and said selectedcommunication primitives that are not already loaded; and d) connectingsaid Application Process with said loaded minor services using saidloaded communication primitives, when the Application Process requiresinteraction with said selected Minor Services; wherein said applicationprocess includes a stub Thread Communication Service, said stub ThreadCommunication Service comprising: Accepting request from saidapplication process; and Communicating to Thread Communication Serviceapplication process said request on behalf of said application process;and wherein said Thread Communication Service application processcomprises: (a) Selecting registered Minor Services and registeredcommunication primitives by chosen criteria; (b) Determining whichselected Minor Services and communications primitives are currentlyloaded; (c) Loading said selected Minor Services and said communicationprimitives that are not already loaded; and (d) Connecting saidapplication process with said loaded Minor Services using said loadedcommunication primitives, when the application process requiresinteraction with said selected Minor Service.
 2. The method of claim 1,further comprising the step of invoking said Minor Service's registeredCREATE function after said Loading step (c).
 3. The method of claim 1,further comprising the step of invoking said Minor Service's registeredCONNECT function after said Loading step (c).
 4. The method of claim 3,wherein, upon invoking the CONNECT function registered for said MinorService, recording the current number of CONNECTED applicationprocesses.
 5. The method of claim 4, wherein the maximum number ofconcurrent communications supported by said Minor Service has beenregistered, said stub Thread Communication Service further comprisingthe steps of: Comparing the number of CURRENT CONNECTED applicationprocesses with the Minor Service's said registered maximum number ofconcurrent communications, and denying connection of said applicationprocess with said loaded Minor Service when the number of CURRENTCONNECTED application processes is equal to said maximum number.